diff --git a/internal/fakechain/fakechain.go b/internal/fakechain/fakechain.go
index 0054d246b..73d0d9746 100644
--- a/internal/fakechain/fakechain.go
+++ b/internal/fakechain/fakechain.go
@@ -327,12 +327,12 @@ func (chain *FakeChain) GetStorageItem(id int32, key []byte) state.StorageItem {
 }
 
 // GetTestVM implements Blockchainer interface.
-func (chain *FakeChain) GetTestVM(t trigger.Type, tx *transaction.Transaction, b *block.Block) *vm.VM {
+func (chain *FakeChain) GetTestVM(t trigger.Type, tx *transaction.Transaction, b *block.Block) (*vm.VM, func()) {
 	panic("TODO")
 }
 
 // GetStorageItems implements Blockchainer interface.
-func (chain *FakeChain) GetStorageItems(id int32) (map[string]state.StorageItem, error) {
+func (chain *FakeChain) GetStorageItems(id int32) ([]state.StorageItemWithKey, error) {
 	panic("TODO")
 }
 
diff --git a/pkg/core/blockchain.go b/pkg/core/blockchain.go
index a5d9aeecd..77543467e 100644
--- a/pkg/core/blockchain.go
+++ b/pkg/core/blockchain.go
@@ -490,9 +490,8 @@ func (bc *Blockchain) jumpToStateInternal(p uint32, stage stateJumpStage) error
 		// Firstly, remove all old genesis-related items.
 		b := bc.dao.Store.Batch()
 		bc.dao.Store.Seek([]byte{byte(storage.STStorage)}, func(k, _ []byte) {
-			// Must copy here, #1468.
-			key := slice.Copy(k)
-			b.Delete(key)
+			// #1468, but don't need to copy here, because it is done by Store.
+			b.Delete(k)
 		})
 		b.Put(jumpStageKey, []byte{byte(oldStorageItemsRemoved)})
 		err := bc.dao.Store.PutBatch(b)
@@ -509,14 +508,12 @@ func (bc *Blockchain) jumpToStateInternal(p uint32, stage stateJumpStage) error
 				if count >= maxStorageBatchSize {
 					return
 				}
-				// Must copy here, #1468.
-				oldKey := slice.Copy(k)
-				b.Delete(oldKey)
+				// #1468, but don't need to copy here, because it is done by Store.
+				b.Delete(k)
 				key := make([]byte, len(k))
 				key[0] = byte(storage.STStorage)
 				copy(key[1:], k[1:])
-				value := slice.Copy(v)
-				b.Put(key, value)
+				b.Put(key, slice.Copy(v))
 				count += 2
 			})
 			if count > 0 {
@@ -1039,7 +1036,7 @@ func (bc *Blockchain) storeBlock(block *block.Block, txpool *mempool.Pool) error
 		v.LoadToken = contract.LoadToken(systemInterop)
 		v.GasLimit = tx.SystemFee
 
-		err := v.Run()
+		err := systemInterop.Exec()
 		var faultException string
 		if !v.HasFailed() {
 			_, err := systemInterop.DAO.Persist()
@@ -1226,7 +1223,7 @@ func (bc *Blockchain) runPersist(script []byte, block *block.Block, cache dao.DA
 	v := systemInterop.SpawnVM()
 	v.LoadScriptWithFlags(script, callflag.All)
 	v.SetPriceGetter(systemInterop.GetPrice)
-	if err := v.Run(); err != nil {
+	if err := systemInterop.Exec(); err != nil {
 		return nil, fmt.Errorf("VM has failed: %w", err)
 	} else if _, err := systemInterop.DAO.Persist(); err != nil {
 		return nil, fmt.Errorf("can't save changes: %w", err)
@@ -1494,7 +1491,7 @@ func (bc *Blockchain) GetStorageItem(id int32, key []byte) state.StorageItem {
 }
 
 // GetStorageItems returns all storage items for a given contract id.
-func (bc *Blockchain) GetStorageItems(id int32) (map[string]state.StorageItem, error) {
+func (bc *Blockchain) GetStorageItems(id int32) ([]state.StorageItemWithKey, error) {
 	return bc.dao.GetStorageItems(id)
 }
 
@@ -2055,14 +2052,14 @@ func (bc *Blockchain) GetEnrollments() ([]state.Validator, error) {
 	return bc.contracts.NEO.GetCandidates(bc.dao)
 }
 
-// GetTestVM returns a VM and a Store setup for a test run of some sort of code.
-func (bc *Blockchain) GetTestVM(t trigger.Type, tx *transaction.Transaction, b *block.Block) *vm.VM {
+// GetTestVM returns a VM setup for a test run of some sort of code and finalizer function.
+func (bc *Blockchain) GetTestVM(t trigger.Type, tx *transaction.Transaction, b *block.Block) (*vm.VM, func()) {
 	d := bc.dao.GetWrapped().(*dao.Simple)
 	systemInterop := bc.newInteropContext(t, d, b, tx)
 	vm := systemInterop.SpawnVM()
 	vm.SetPriceGetter(systemInterop.GetPrice)
 	vm.LoadToken = contract.LoadToken(systemInterop)
-	return vm
+	return vm, systemInterop.Finalize
 }
 
 // Various witness verification errors.
@@ -2141,7 +2138,7 @@ func (bc *Blockchain) verifyHashAgainstScript(hash util.Uint160, witness *transa
 	if err := bc.InitVerificationVM(vm, interopCtx.GetContract, hash, witness); err != nil {
 		return 0, err
 	}
-	err := vm.Run()
+	err := interopCtx.Exec()
 	if vm.HasFailed() {
 		return 0, fmt.Errorf("%w: vm execution has failed: %v", ErrVerificationFailed, err)
 	}
diff --git a/pkg/core/blockchainer/blockchainer.go b/pkg/core/blockchainer/blockchainer.go
index 97bd64611..b63bca04c 100644
--- a/pkg/core/blockchainer/blockchainer.go
+++ b/pkg/core/blockchainer/blockchainer.go
@@ -58,8 +58,8 @@ type Blockchainer interface {
 	GetStateModule() StateRoot
 	GetStateSyncModule() StateSync
 	GetStorageItem(id int32, key []byte) state.StorageItem
-	GetStorageItems(id int32) (map[string]state.StorageItem, error)
-	GetTestVM(t trigger.Type, tx *transaction.Transaction, b *block.Block) *vm.VM
+	GetStorageItems(id int32) ([]state.StorageItemWithKey, error)
+	GetTestVM(t trigger.Type, tx *transaction.Transaction, b *block.Block) (*vm.VM, func())
 	GetTransaction(util.Uint256) (*transaction.Transaction, uint32, error)
 	SetOracle(service services.Oracle)
 	mempool.Feer // fee interface
diff --git a/pkg/core/dao/dao.go b/pkg/core/dao/dao.go
index 2a509344f..b15a36e97 100644
--- a/pkg/core/dao/dao.go
+++ b/pkg/core/dao/dao.go
@@ -2,6 +2,7 @@ package dao
 
 import (
 	"bytes"
+	"context"
 	"encoding/binary"
 	"errors"
 	"fmt"
@@ -16,7 +17,6 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/io"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract/trigger"
 	"github.com/nspcc-dev/neo-go/pkg/util"
-	"github.com/nspcc-dev/neo-go/pkg/util/slice"
 )
 
 // HasTransaction errors.
@@ -48,8 +48,8 @@ type DAO interface {
 	GetStateSyncPoint() (uint32, error)
 	GetStateSyncCurrentBlockHeight() (uint32, error)
 	GetStorageItem(id int32, key []byte) state.StorageItem
-	GetStorageItems(id int32) (map[string]state.StorageItem, error)
-	GetStorageItemsWithPrefix(id int32, prefix []byte) (map[string]state.StorageItem, error)
+	GetStorageItems(id int32) ([]state.StorageItemWithKey, error)
+	GetStorageItemsWithPrefix(id int32, prefix []byte) ([]state.StorageItemWithKey, error)
 	GetTransaction(hash util.Uint256) (*transaction.Transaction, uint32, error)
 	GetVersion() (string, error)
 	GetWrapped() DAO
@@ -65,6 +65,7 @@ type DAO interface {
 	PutStorageItem(id int32, key []byte, si state.StorageItem) error
 	PutVersion(v string) error
 	Seek(id int32, prefix []byte, f func(k, v []byte))
+	SeekAsync(ctx context.Context, id int32, prefix []byte) chan storage.KeyValue
 	StoreAsBlock(block *block.Block, buf *io.BufBinWriter) error
 	StoreAsCurrentBlock(block *block.Block, buf *io.BufBinWriter) error
 	StoreAsTransaction(tx *transaction.Transaction, index uint32, buf *io.BufBinWriter) error
@@ -313,28 +314,29 @@ func (dao *Simple) DeleteStorageItem(id int32, key []byte) error {
 }
 
 // GetStorageItems returns all storage items for a given id.
-func (dao *Simple) GetStorageItems(id int32) (map[string]state.StorageItem, error) {
+func (dao *Simple) GetStorageItems(id int32) ([]state.StorageItemWithKey, error) {
 	return dao.GetStorageItemsWithPrefix(id, nil)
 }
 
 // GetStorageItemsWithPrefix returns all storage items with given id for a
 // given scripthash.
-func (dao *Simple) GetStorageItemsWithPrefix(id int32, prefix []byte) (map[string]state.StorageItem, error) {
-	var siMap = make(map[string]state.StorageItem)
+func (dao *Simple) GetStorageItemsWithPrefix(id int32, prefix []byte) ([]state.StorageItemWithKey, error) {
+	var siArr []state.StorageItemWithKey
 
-	saveToMap := func(k, v []byte) {
+	saveToArr := func(k, v []byte) {
 		// Cut prefix and hash.
-		// Must copy here, #1468.
-		key := slice.Copy(k)
-		val := slice.Copy(v)
-		siMap[string(key)] = state.StorageItem(val)
+		// #1468, but don't need to copy here, because it is done by Store.
+		siArr = append(siArr, state.StorageItemWithKey{
+			Key:  k,
+			Item: state.StorageItem(v),
+		})
 	}
-	dao.Seek(id, prefix, saveToMap)
-	return siMap, nil
+	dao.Seek(id, prefix, saveToArr)
+	return siArr, nil
 }
 
 // Seek executes f for all items with a given prefix.
-// If key is to be used outside of f, they must be copied.
+// If key is to be used outside of f, they may not be copied.
 func (dao *Simple) Seek(id int32, prefix []byte, f func(k, v []byte)) {
 	lookupKey := makeStorageItemKey(id, nil)
 	if prefix != nil {
@@ -345,6 +347,16 @@ func (dao *Simple) Seek(id int32, prefix []byte, f func(k, v []byte)) {
 	})
 }
 
+// SeekAsync sends all storage items matching given prefix to a channel and returns
+// the channel. Resulting keys and values may not be copied.
+func (dao *Simple) SeekAsync(ctx context.Context, id int32, prefix []byte) chan storage.KeyValue {
+	lookupKey := makeStorageItemKey(id, nil)
+	if prefix != nil {
+		lookupKey = append(lookupKey, prefix...)
+	}
+	return dao.Store.SeekAsync(ctx, lookupKey, true)
+}
+
 // makeStorageItemKey returns a key used to store StorageItem in the DB.
 func makeStorageItemKey(id int32, key []byte) []byte {
 	// 1 for prefix + 4 for Uint32 + len(key) for key
diff --git a/pkg/core/interop/context.go b/pkg/core/interop/context.go
index 908b8a6ac..1c7a3ad6e 100644
--- a/pkg/core/interop/context.go
+++ b/pkg/core/interop/context.go
@@ -1,6 +1,7 @@
 package interop
 
 import (
+	"context"
 	"encoding/binary"
 	"errors"
 	"fmt"
@@ -47,6 +48,7 @@ type Context struct {
 	Log           *zap.Logger
 	VM            *vm.VM
 	Functions     []Function
+	cancelFuncs   []context.CancelFunc
 	getContract   func(dao.DAO, util.Uint160) (*state.Contract, error)
 	baseExecFee   int64
 }
@@ -285,3 +287,25 @@ func (ic *Context) SpawnVM() *vm.VM {
 	ic.VM = v
 	return v
 }
+
+// RegisterCancelFunc adds given function to the list of functions to be called after VM
+// finishes script execution.
+func (ic *Context) RegisterCancelFunc(f context.CancelFunc) {
+	if f != nil {
+		ic.cancelFuncs = append(ic.cancelFuncs, f)
+	}
+}
+
+// Finalize calls all registered cancel functions to release the occupied resources.
+func (ic *Context) Finalize() {
+	for _, f := range ic.cancelFuncs {
+		f()
+	}
+	ic.cancelFuncs = nil
+}
+
+// Exec executes loaded VM script and calls registered finalizers to release the occupied resources.
+func (ic *Context) Exec() error {
+	defer ic.Finalize()
+	return ic.VM.Run()
+}
diff --git a/pkg/core/interop/storage/find.go b/pkg/core/interop/storage/find.go
index 045c9290f..35b6621f4 100644
--- a/pkg/core/interop/storage/find.go
+++ b/pkg/core/interop/storage/find.go
@@ -1,6 +1,10 @@
 package storage
 
-import "github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
+import (
+	"github.com/nspcc-dev/neo-go/pkg/core/storage"
+	"github.com/nspcc-dev/neo-go/pkg/util/slice"
+	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
+)
 
 // Storage iterator options.
 const (
@@ -18,44 +22,45 @@ const (
 
 // Iterator is an iterator state representation.
 type Iterator struct {
-	m          []stackitem.MapElement
-	opts       int64
-	index      int
-	prefixSize int
+	seekCh chan storage.KeyValue
+	curr   storage.KeyValue
+	next   bool
+	opts   int64
+	prefix []byte
 }
 
-// NewIterator creates a new Iterator with given options for a given map.
-func NewIterator(m *stackitem.Map, prefix int, opts int64) *Iterator {
+// NewIterator creates a new Iterator with given options for a given channel of store.Seek results.
+func NewIterator(seekCh chan storage.KeyValue, prefix []byte, opts int64) *Iterator {
 	return &Iterator{
-		m:          m.Value().([]stackitem.MapElement),
-		opts:       opts,
-		index:      -1,
-		prefixSize: prefix,
+		seekCh: seekCh,
+		opts:   opts,
+		prefix: slice.Copy(prefix),
 	}
 }
 
 // Next advances the iterator and returns true if Value can be called at the
 // current position.
 func (s *Iterator) Next() bool {
-	if s.index < len(s.m) {
-		s.index++
-	}
-	return s.index < len(s.m)
+	s.curr, s.next = <-s.seekCh
+	return s.next
 }
 
 // Value returns current iterators value (exact type depends on options this
 // iterator was created with).
 func (s *Iterator) Value() stackitem.Item {
-	key := s.m[s.index].Key.Value().([]byte)
-	if s.opts&FindRemovePrefix != 0 {
-		key = key[s.prefixSize:]
+	if !s.next {
+		panic("iterator index out of range")
+	}
+	key := s.curr.Key
+	if s.opts&FindRemovePrefix == 0 {
+		key = append(s.prefix, key...)
 	}
 	if s.opts&FindKeysOnly != 0 {
 		return stackitem.NewByteArray(key)
 	}
-	value := s.m[s.index].Value
+	value := stackitem.Item(stackitem.NewByteArray(s.curr.Value))
 	if s.opts&FindDeserialize != 0 {
-		bs := s.m[s.index].Value.Value().([]byte)
+		bs := s.curr.Value
 		var err error
 		value, err = stackitem.Deserialize(bs)
 		if err != nil {
diff --git a/pkg/core/interop_system.go b/pkg/core/interop_system.go
index a56ef18cd..fd473b65b 100644
--- a/pkg/core/interop_system.go
+++ b/pkg/core/interop_system.go
@@ -1,13 +1,12 @@
 package core
 
 import (
-	"bytes"
+	"context"
 	"crypto/elliptic"
 	"errors"
 	"fmt"
 	"math"
 	"math/big"
-	"sort"
 
 	"github.com/nspcc-dev/neo-go/pkg/core/block"
 	"github.com/nspcc-dev/neo-go/pkg/core/interop"
@@ -188,30 +187,13 @@ func storageFind(ic *interop.Context) error {
 	if opts&istorage.FindDeserialize == 0 && (opts&istorage.FindPick0 != 0 || opts&istorage.FindPick1 != 0) {
 		return fmt.Errorf("%w: PickN is specified without Deserialize", errFindInvalidOptions)
 	}
-	siMap, err := ic.DAO.GetStorageItemsWithPrefix(stc.ID, prefix)
-	if err != nil {
-		return err
-	}
-
-	arr := make([]stackitem.MapElement, 0, len(siMap))
-	for k, v := range siMap {
-		keycopy := make([]byte, len(k)+len(prefix))
-		copy(keycopy, prefix)
-		copy(keycopy[len(prefix):], k)
-		arr = append(arr, stackitem.MapElement{
-			Key:   stackitem.NewByteArray(keycopy),
-			Value: stackitem.NewByteArray(v),
-		})
-	}
-	sort.Slice(arr, func(i, j int) bool {
-		k1 := arr[i].Key.Value().([]byte)
-		k2 := arr[j].Key.Value().([]byte)
-		return bytes.Compare(k1, k2) == -1
-	})
-
-	filteredMap := stackitem.NewMapWithValue(arr)
-	item := istorage.NewIterator(filteredMap, len(prefix), opts)
+	// Items in seekres should be sorted by key, but GetStorageItemsWithPrefix returns
+	// sorted items, so no need to sort them one more time.
+	ctx, cancel := context.WithCancel(context.Background())
+	seekres := ic.DAO.SeekAsync(ctx, stc.ID, prefix)
+	item := istorage.NewIterator(seekres, prefix, opts)
 	ic.VM.Estack().PushItem(stackitem.NewInterop(item))
+	ic.RegisterCancelFunc(cancel)
 
 	return nil
 }
diff --git a/pkg/core/interop_system_test.go b/pkg/core/interop_system_test.go
index 809f38b12..f86b73858 100644
--- a/pkg/core/interop_system_test.go
+++ b/pkg/core/interop_system_test.go
@@ -2,6 +2,7 @@ package core
 
 import (
 	"errors"
+	"fmt"
 	"math"
 	"math/big"
 	"testing"
@@ -336,32 +337,101 @@ func TestStorageDelete(t *testing.T) {
 }
 
 func BenchmarkStorageFind(b *testing.B) {
-	v, contractState, context, chain := createVMAndContractState(b)
-	require.NoError(b, chain.contracts.Management.PutContractState(chain.dao, contractState))
+	for count := 10; count <= 10000; count *= 10 {
+		b.Run(fmt.Sprintf("%dElements", count), func(b *testing.B) {
+			v, contractState, context, chain := createVMAndContractState(b)
+			require.NoError(b, chain.contracts.Management.PutContractState(chain.dao, contractState))
 
-	const count = 100
+			items := make(map[string]state.StorageItem)
+			for i := 0; i < count; i++ {
+				items["abc"+random.String(10)] = random.Bytes(10)
+			}
+			for k, v := range items {
+				require.NoError(b, context.DAO.PutStorageItem(contractState.ID, []byte(k), v))
+				require.NoError(b, context.DAO.PutStorageItem(contractState.ID+1, []byte(k), v))
+			}
+			changes, err := context.DAO.Persist()
+			require.NoError(b, err)
+			require.NotEqual(b, 0, changes)
 
-	items := make(map[string]state.StorageItem)
-	for i := 0; i < count; i++ {
-		items["abc"+random.String(10)] = random.Bytes(10)
-	}
-	for k, v := range items {
-		require.NoError(b, context.DAO.PutStorageItem(contractState.ID, []byte(k), v))
-		require.NoError(b, context.DAO.PutStorageItem(contractState.ID+1, []byte(k), v))
+			b.ResetTimer()
+			b.ReportAllocs()
+			for i := 0; i < b.N; i++ {
+				b.StopTimer()
+				v.Estack().PushVal(istorage.FindDefault)
+				v.Estack().PushVal("abc")
+				v.Estack().PushVal(stackitem.NewInterop(&StorageContext{ID: contractState.ID}))
+				b.StartTimer()
+				err := storageFind(context)
+				if err != nil {
+					b.FailNow()
+				}
+				b.StopTimer()
+				context.Finalize()
+			}
+		})
 	}
+}
 
-	b.ResetTimer()
-	b.ReportAllocs()
-	for i := 0; i < b.N; i++ {
-		b.StopTimer()
-		v.Estack().PushVal(istorage.FindDefault)
-		v.Estack().PushVal("abc")
-		v.Estack().PushVal(stackitem.NewInterop(&StorageContext{ID: contractState.ID}))
-		b.StartTimer()
-		err := storageFind(context)
-		if err != nil {
-			b.FailNow()
+func BenchmarkStorageFindIteratorNext(b *testing.B) {
+	for count := 10; count <= 10000; count *= 10 {
+		cases := map[string]int{
+			"Pick1":    1,
+			"PickHalf": count / 2,
+			"PickAll":  count,
 		}
+		b.Run(fmt.Sprintf("%dElements", count), func(b *testing.B) {
+			for name, last := range cases {
+				b.Run(name, func(b *testing.B) {
+					v, contractState, context, chain := createVMAndContractState(b)
+					require.NoError(b, chain.contracts.Management.PutContractState(chain.dao, contractState))
+
+					items := make(map[string]state.StorageItem)
+					for i := 0; i < count; i++ {
+						items["abc"+random.String(10)] = random.Bytes(10)
+					}
+					for k, v := range items {
+						require.NoError(b, context.DAO.PutStorageItem(contractState.ID, []byte(k), v))
+						require.NoError(b, context.DAO.PutStorageItem(contractState.ID+1, []byte(k), v))
+					}
+					changes, err := context.DAO.Persist()
+					require.NoError(b, err)
+					require.NotEqual(b, 0, changes)
+					b.ReportAllocs()
+					b.ResetTimer()
+					for i := 0; i < b.N; i++ {
+						b.StopTimer()
+						v.Estack().PushVal(istorage.FindDefault)
+						v.Estack().PushVal("abc")
+						v.Estack().PushVal(stackitem.NewInterop(&StorageContext{ID: contractState.ID}))
+						b.StartTimer()
+						err := storageFind(context)
+						b.StopTimer()
+						if err != nil {
+							b.FailNow()
+						}
+						res := context.VM.Estack().Pop().Item()
+						for i := 0; i < last; i++ {
+							context.VM.Estack().PushVal(res)
+							b.StartTimer()
+							require.NoError(b, iterator.Next(context))
+							b.StopTimer()
+							require.True(b, context.VM.Estack().Pop().Bool())
+						}
+
+						context.VM.Estack().PushVal(res)
+						require.NoError(b, iterator.Next(context))
+						actual := context.VM.Estack().Pop().Bool()
+						if last == count {
+							require.False(b, actual)
+						} else {
+							require.True(b, actual)
+						}
+						context.Finalize()
+					}
+				})
+			}
+		})
 	}
 }
 
diff --git a/pkg/core/native/designate.go b/pkg/core/native/designate.go
index 844690a3d..ccf5767b8 100644
--- a/pkg/core/native/designate.go
+++ b/pkg/core/native/designate.go
@@ -257,17 +257,22 @@ func (s *Designate) GetDesignatedByRole(d dao.DAO, r noderoles.Role, index uint3
 	if err != nil {
 		return nil, 0, err
 	}
-	var ns NodeList
-	var bestIndex uint32
-	var resSi state.StorageItem
-	for k, si := range kvs {
-		if len(k) < 4 {
+	var (
+		ns        NodeList
+		bestIndex uint32
+		resSi     state.StorageItem
+	)
+	// kvs are sorted by key (BE index bytes) in ascending way, so iterate backwards to get the latest designated.
+	for i := len(kvs) - 1; i >= 0; i-- {
+		kv := kvs[i]
+		if len(kv.Key) < 4 {
 			continue
 		}
-		siInd := binary.BigEndian.Uint32([]byte(k))
-		if (resSi == nil || siInd > bestIndex) && siInd <= index {
+		siInd := binary.BigEndian.Uint32(kv.Key)
+		if siInd <= index {
 			bestIndex = siInd
-			resSi = si
+			resSi = kv.Item
+			break
 		}
 	}
 	if resSi != nil {
diff --git a/pkg/core/native/management.go b/pkg/core/native/management.go
index c66e9dc8d..7403559e7 100644
--- a/pkg/core/native/management.go
+++ b/pkg/core/native/management.go
@@ -391,12 +391,12 @@ func (m *Management) Destroy(d dao.DAO, hash util.Uint160) error {
 	if err != nil {
 		return err
 	}
-	siMap, err := d.GetStorageItems(contract.ID)
+	siArr, err := d.GetStorageItems(contract.ID)
 	if err != nil {
 		return err
 	}
-	for k := range siMap {
-		err := d.DeleteStorageItem(contract.ID, []byte(k))
+	for _, kv := range siArr {
+		err := d.DeleteStorageItem(contract.ID, []byte(kv.Key))
 		if err != nil {
 			return err
 		}
diff --git a/pkg/core/native/native_neo.go b/pkg/core/native/native_neo.go
index 9df6e468b..53604bca3 100644
--- a/pkg/core/native/native_neo.go
+++ b/pkg/core/native/native_neo.go
@@ -471,24 +471,20 @@ func (n *NEO) getGASPerBlock(ic *interop.Context, _ []stackitem.Item) stackitem.
 }
 
 func (n *NEO) getSortedGASRecordFromDAO(d dao.DAO) (gasRecord, error) {
-	grMap, err := d.GetStorageItemsWithPrefix(n.ID, []byte{prefixGASPerBlock})
+	grArr, err := d.GetStorageItemsWithPrefix(n.ID, []byte{prefixGASPerBlock})
 	if err != nil {
 		return gasRecord{}, fmt.Errorf("failed to get gas records from storage: %w", err)
 	}
-	var (
-		i  int
-		gr = make(gasRecord, len(grMap))
-	)
-	for indexBytes, gasValue := range grMap {
+	var gr = make(gasRecord, len(grArr))
+	for i, kv := range grArr {
+		indexBytes, gasValue := kv.Key, kv.Item
 		gr[i] = gasIndexPair{
 			Index:       binary.BigEndian.Uint32([]byte(indexBytes)),
 			GASPerBlock: *bigint.FromBytes(gasValue),
 		}
-		i++
 	}
-	sort.Slice(gr, func(i, j int) bool {
-		return gr[i].Index < gr[j].Index
-	})
+	// GAS records should be sorted by index, but GetStorageItemsWithPrefix returns
+	// values sorted by BE bytes of index, so we're OK with that.
 	return gr, nil
 }
 
@@ -836,21 +832,21 @@ func (n *NEO) ModifyAccountVotes(acc *state.NEOBalance, d dao.DAO, value *big.In
 }
 
 func (n *NEO) getCandidates(d dao.DAO, sortByKey bool) ([]keyWithVotes, error) {
-	siMap, err := d.GetStorageItemsWithPrefix(n.ID, []byte{prefixCandidate})
+	siArr, err := d.GetStorageItemsWithPrefix(n.ID, []byte{prefixCandidate})
 	if err != nil {
 		return nil, err
 	}
-	arr := make([]keyWithVotes, 0, len(siMap))
-	for key, si := range siMap {
-		c := new(candidate).FromBytes(si)
+	arr := make([]keyWithVotes, 0, len(siArr))
+	for _, kv := range siArr {
+		c := new(candidate).FromBytes(kv.Item)
 		if c.Registered {
-			arr = append(arr, keyWithVotes{Key: key, Votes: &c.Votes})
+			arr = append(arr, keyWithVotes{Key: string(kv.Key), Votes: &c.Votes})
 		}
 	}
-	if sortByKey {
-		// Sort by serialized key bytes (that's the way keys are stored and retrieved from the storage by default).
-		sort.Slice(arr, func(i, j int) bool { return strings.Compare(arr[i].Key, arr[j].Key) == -1 })
-	} else {
+	if !sortByKey {
+		// sortByKey assumes to sort by serialized key bytes (that's the way keys
+		// are stored and retrieved from the storage by default). Otherwise, need
+		// to sort using big.Int comparator.
 		sort.Slice(arr, func(i, j int) bool {
 			// The most-voted validators should end up in the front of the list.
 			cmp := arr[i].Votes.Cmp(arr[j].Votes)
diff --git a/pkg/core/native/oracle.go b/pkg/core/native/oracle.go
index c060a9739..393c0d979 100644
--- a/pkg/core/native/oracle.go
+++ b/pkg/core/native/oracle.go
@@ -483,21 +483,21 @@ func (o *Oracle) getOriginalTxID(d dao.DAO, tx *transaction.Transaction) util.Ui
 
 // getRequests returns all requests which have not been finished yet.
 func (o *Oracle) getRequests(d dao.DAO) (map[uint64]*state.OracleRequest, error) {
-	m, err := d.GetStorageItemsWithPrefix(o.ID, prefixRequest)
+	arr, err := d.GetStorageItemsWithPrefix(o.ID, prefixRequest)
 	if err != nil {
 		return nil, err
 	}
-	reqs := make(map[uint64]*state.OracleRequest, len(m))
-	for k, si := range m {
-		if len(k) != 8 {
+	reqs := make(map[uint64]*state.OracleRequest, len(arr))
+	for _, kv := range arr {
+		if len(kv.Key) != 8 {
 			return nil, errors.New("invalid request ID")
 		}
 		req := new(state.OracleRequest)
-		err = stackitem.DeserializeConvertible(si, req)
+		err = stackitem.DeserializeConvertible(kv.Item, req)
 		if err != nil {
 			return nil, err
 		}
-		id := binary.BigEndian.Uint64([]byte(k))
+		id := binary.BigEndian.Uint64([]byte(kv.Key))
 		reqs[id] = req
 	}
 	return reqs, nil
diff --git a/pkg/core/native/policy.go b/pkg/core/native/policy.go
index e377f0447..dffe1371c 100644
--- a/pkg/core/native/policy.go
+++ b/pkg/core/native/policy.go
@@ -162,20 +162,20 @@ func (p *Policy) PostPersist(ic *interop.Context) error {
 	p.storagePrice = uint32(getIntWithKey(p.ID, ic.DAO, storagePriceKey))
 
 	p.blockedAccounts = make([]util.Uint160, 0)
-	siMap, err := ic.DAO.GetStorageItemsWithPrefix(p.ID, []byte{blockedAccountPrefix})
+	siArr, err := ic.DAO.GetStorageItemsWithPrefix(p.ID, []byte{blockedAccountPrefix})
 	if err != nil {
 		return fmt.Errorf("failed to get blocked accounts from storage: %w", err)
 	}
-	for key := range siMap {
-		hash, err := util.Uint160DecodeBytesBE([]byte(key))
+	for _, kv := range siArr {
+		hash, err := util.Uint160DecodeBytesBE([]byte(kv.Key))
 		if err != nil {
 			return fmt.Errorf("failed to decode blocked account hash: %w", err)
 		}
 		p.blockedAccounts = append(p.blockedAccounts, hash)
 	}
-	sort.Slice(p.blockedAccounts, func(i, j int) bool {
-		return p.blockedAccounts[i].Less(p.blockedAccounts[j])
-	})
+	// blockedAccounts should be sorted by account BE bytes, but GetStorageItemsWithPrefix
+	// returns values sorted by key (which is account's BE bytes), so don't need to sort
+	// one more time.
 
 	p.isValid = true
 	return nil
diff --git a/pkg/core/state/storage_item.go b/pkg/core/state/storage_item.go
index ba9777cf8..0a6eebb23 100644
--- a/pkg/core/state/storage_item.go
+++ b/pkg/core/state/storage_item.go
@@ -2,3 +2,9 @@ package state
 
 // StorageItem is the value to be stored with read-only flag.
 type StorageItem []byte
+
+// StorageItemWithKey is a storage item with corresponding key.
+type StorageItemWithKey struct {
+	Key  []byte
+	Item StorageItem
+}
diff --git a/pkg/core/stateroot/module.go b/pkg/core/stateroot/module.go
index a96bac1f1..fdc053595 100644
--- a/pkg/core/stateroot/module.go
+++ b/pkg/core/stateroot/module.go
@@ -13,7 +13,6 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/core/storage"
 	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
 	"github.com/nspcc-dev/neo-go/pkg/util"
-	"github.com/nspcc-dev/neo-go/pkg/util/slice"
 	"go.uber.org/atomic"
 	"go.uber.org/zap"
 )
@@ -147,9 +146,8 @@ func (s *Module) CleanStorage() error {
 	//
 	b := s.Store.Batch()
 	s.Store.Seek([]byte{byte(storage.DataMPT)}, func(k, _ []byte) {
-		// Must copy here, #1468.
-		key := slice.Copy(k)
-		b.Delete(key)
+		// #1468, but don't need to copy here, because it is done by Store.
+		b.Delete(k)
 	})
 	err = s.Store.PutBatch(b)
 	if err != nil {
diff --git a/pkg/core/storage/badgerdb_store_test.go b/pkg/core/storage/badgerdb_store_test.go
index e00fa4a15..78a8fb957 100644
--- a/pkg/core/storage/badgerdb_store_test.go
+++ b/pkg/core/storage/badgerdb_store_test.go
@@ -6,7 +6,7 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func newBadgerDBForTesting(t *testing.T) Store {
+func newBadgerDBForTesting(t testing.TB) Store {
 	bdbDir := t.TempDir()
 	dbConfig := DBConfiguration{
 		Type: "badgerdb",
diff --git a/pkg/core/storage/boltdb_store_test.go b/pkg/core/storage/boltdb_store_test.go
index 9f8fd4caf..cd1a84e39 100644
--- a/pkg/core/storage/boltdb_store_test.go
+++ b/pkg/core/storage/boltdb_store_test.go
@@ -7,7 +7,7 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func newBoltStoreForTesting(t *testing.T) Store {
+func newBoltStoreForTesting(t testing.TB) Store {
 	d := t.TempDir()
 	testFileName := path.Join(d, "test_bolt_db")
 	boltDBStore, err := NewBoltDBStore(BoltDBOptions{FilePath: testFileName})
diff --git a/pkg/core/storage/leveldb_store_test.go b/pkg/core/storage/leveldb_store_test.go
index 5d8672e7a..24f21e76b 100644
--- a/pkg/core/storage/leveldb_store_test.go
+++ b/pkg/core/storage/leveldb_store_test.go
@@ -6,7 +6,7 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func newLevelDBForTesting(t *testing.T) Store {
+func newLevelDBForTesting(t testing.TB) Store {
 	ldbDir := t.TempDir()
 	dbConfig := DBConfiguration{
 		Type: "leveldb",
diff --git a/pkg/core/storage/memcached_store.go b/pkg/core/storage/memcached_store.go
index b21d3edaa..afe32481b 100644
--- a/pkg/core/storage/memcached_store.go
+++ b/pkg/core/storage/memcached_store.go
@@ -1,6 +1,14 @@
 package storage
 
-import "sync"
+import (
+	"bytes"
+	"context"
+	"sort"
+	"strings"
+	"sync"
+
+	"github.com/nspcc-dev/neo-go/pkg/util/slice"
+)
 
 // MemCachedStore is a wrapper around persistent store that caches all changes
 // being made for them to be later flushed in one batch.
@@ -18,14 +26,20 @@ type (
 	KeyValue struct {
 		Key   []byte
 		Value []byte
+	}
+
+	// KeyValueExists represents key-value pair with indicator whether the item
+	// exists in the persistent storage.
+	KeyValueExists struct {
+		KeyValue
 
 		Exists bool
 	}
 
 	// MemBatch represents a changeset to be persisted.
 	MemBatch struct {
-		Put     []KeyValue
-		Deleted []KeyValue
+		Put     []KeyValueExists
+		Deleted []KeyValueExists
 	}
 )
 
@@ -58,18 +72,18 @@ func (s *MemCachedStore) GetBatch() *MemBatch {
 
 	var b MemBatch
 
-	b.Put = make([]KeyValue, 0, len(s.mem))
+	b.Put = make([]KeyValueExists, 0, len(s.mem))
 	for k, v := range s.mem {
 		key := []byte(k)
 		_, err := s.ps.Get(key)
-		b.Put = append(b.Put, KeyValue{Key: key, Value: v, Exists: err == nil})
+		b.Put = append(b.Put, KeyValueExists{KeyValue: KeyValue{Key: key, Value: v}, Exists: err == nil})
 	}
 
-	b.Deleted = make([]KeyValue, 0, len(s.del))
+	b.Deleted = make([]KeyValueExists, 0, len(s.del))
 	for k := range s.del {
 		key := []byte(k)
 		_, err := s.ps.Get(key)
-		b.Deleted = append(b.Deleted, KeyValue{Key: key, Exists: err == nil})
+		b.Deleted = append(b.Deleted, KeyValueExists{KeyValue: KeyValue{Key: key}, Exists: err == nil})
 	}
 
 	return &b
@@ -77,21 +91,130 @@ func (s *MemCachedStore) GetBatch() *MemBatch {
 
 // Seek implements the Store interface.
 func (s *MemCachedStore) Seek(key []byte, f func(k, v []byte)) {
+	s.seek(context.Background(), key, false, f)
+}
+
+// SeekAsync returns non-buffered channel with matching KeyValue pairs. Key and
+// value slices may not be copied and may be modified. SeekAsync can guarantee
+// that key-value items are sorted by key in ascending way.
+func (s *MemCachedStore) SeekAsync(ctx context.Context, key []byte, cutPrefix bool) chan KeyValue {
+	res := make(chan KeyValue)
+	go func() {
+		s.seek(ctx, key, cutPrefix, func(k, v []byte) {
+			res <- KeyValue{
+				Key:   k,
+				Value: v,
+			}
+		})
+		close(res)
+	}()
+
+	return res
+}
+
+func (s *MemCachedStore) seek(ctx context.Context, key []byte, cutPrefix bool, f func(k, v []byte)) {
+	// Create memory store `mem` and `del` snapshot not to hold the lock.
+	var memRes []KeyValueExists
+	sk := string(key)
 	s.mut.RLock()
-	defer s.mut.RUnlock()
-	s.MemoryStore.seek(key, f)
-	s.ps.Seek(key, func(k, v []byte) {
-		elem := string(k)
-		// If it's in mem, we already called f() for it in MemoryStore.Seek().
-		_, present := s.mem[elem]
-		if !present {
-			// If it's in del, we shouldn't be calling f() anyway.
-			_, present = s.del[elem]
+	for k, v := range s.MemoryStore.mem {
+		if strings.HasPrefix(k, sk) {
+			memRes = append(memRes, KeyValueExists{
+				KeyValue: KeyValue{
+					Key:   []byte(k),
+					Value: v,
+				},
+				Exists: true,
+			})
 		}
-		if !present {
-			f(k, v)
+	}
+	for k := range s.MemoryStore.del {
+		if strings.HasPrefix(k, sk) {
+			memRes = append(memRes, KeyValueExists{
+				KeyValue: KeyValue{
+					Key: []byte(k),
+				},
+			})
+		}
+	}
+	ps := s.ps
+	s.mut.RUnlock()
+	// Sort memRes items for further comparison with ps items.
+	sort.Slice(memRes, func(i, j int) bool {
+		return bytes.Compare(memRes[i].Key, memRes[j].Key) < 0
+	})
+
+	var (
+		done    bool
+		iMem    int
+		kvMem   KeyValueExists
+		haveMem bool
+	)
+	if iMem < len(memRes) {
+		kvMem = memRes[iMem]
+		haveMem = true
+		iMem++
+	}
+	// Merge results of seek operations in ascending order.
+	ps.Seek(key, func(k, v []byte) {
+		if done {
+			return
+		}
+		kvPs := KeyValue{
+			Key:   slice.Copy(k),
+			Value: slice.Copy(v),
+		}
+	loop:
+		for {
+			select {
+			case <-ctx.Done():
+				done = true
+				break loop
+			default:
+				var isMem = haveMem && (bytes.Compare(kvMem.Key, kvPs.Key) < 0)
+				if isMem {
+					if kvMem.Exists {
+						if cutPrefix {
+							kvMem.Key = kvMem.Key[len(key):]
+						}
+						f(kvMem.Key, kvMem.Value)
+					}
+					if iMem < len(memRes) {
+						kvMem = memRes[iMem]
+						haveMem = true
+						iMem++
+					} else {
+						haveMem = false
+					}
+				} else {
+					if !bytes.Equal(kvMem.Key, kvPs.Key) {
+						if cutPrefix {
+							kvPs.Key = kvPs.Key[len(key):]
+						}
+						f(kvPs.Key, kvPs.Value)
+					}
+					break loop
+				}
+			}
 		}
 	})
+	if !done && haveMem {
+	loop:
+		for i := iMem - 1; i < len(memRes); i++ {
+			select {
+			case <-ctx.Done():
+				break loop
+			default:
+				kvMem = memRes[i]
+				if kvMem.Exists {
+					if cutPrefix {
+						kvMem.Key = kvMem.Key[len(key):]
+					}
+					f(kvMem.Key, kvMem.Value)
+				}
+			}
+		}
+	}
 }
 
 // Persist flushes all the MemoryStore contents into the (supposedly) persistent
diff --git a/pkg/core/storage/memcached_store_test.go b/pkg/core/storage/memcached_store_test.go
index fe811f61d..216c6b8e7 100644
--- a/pkg/core/storage/memcached_store_test.go
+++ b/pkg/core/storage/memcached_store_test.go
@@ -1,8 +1,13 @@
 package storage
 
 import (
+	"bytes"
+	"fmt"
+	"sort"
 	"testing"
 
+	"github.com/nspcc-dev/neo-go/internal/random"
+	"github.com/nspcc-dev/neo-go/pkg/util/slice"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -16,7 +21,7 @@ func testMemCachedStorePersist(t *testing.T, ps Store) {
 	assert.Equal(t, 0, c)
 	// persisting one key should result in one key in ps and nothing in ts
 	assert.NoError(t, ts.Put([]byte("key"), []byte("value")))
-	checkBatch(t, ts, []KeyValue{{Key: []byte("key"), Value: []byte("value")}}, nil)
+	checkBatch(t, ts, []KeyValueExists{{KeyValue: KeyValue{Key: []byte("key"), Value: []byte("value")}}}, nil)
 	c, err = ts.Persist()
 	checkBatch(t, ts, nil, nil)
 	assert.Equal(t, nil, err)
@@ -35,9 +40,9 @@ func testMemCachedStorePersist(t *testing.T, ps Store) {
 	v, err = ps.Get([]byte("key2"))
 	assert.Equal(t, ErrKeyNotFound, err)
 	assert.Equal(t, []byte(nil), v)
-	checkBatch(t, ts, []KeyValue{
-		{Key: []byte("key"), Value: []byte("newvalue"), Exists: true},
-		{Key: []byte("key2"), Value: []byte("value2")},
+	checkBatch(t, ts, []KeyValueExists{
+		{KeyValue: KeyValue{Key: []byte("key"), Value: []byte("newvalue")}, Exists: true},
+		{KeyValue: KeyValue{Key: []byte("key2"), Value: []byte("value2")}},
 	}, nil)
 	// two keys should be persisted (one overwritten and one new) and
 	// available in the ps
@@ -65,7 +70,7 @@ func testMemCachedStorePersist(t *testing.T, ps Store) {
 	// test persisting deletions
 	err = ts.Delete([]byte("key"))
 	assert.Equal(t, nil, err)
-	checkBatch(t, ts, nil, []KeyValue{{Key: []byte("key"), Exists: true}})
+	checkBatch(t, ts, nil, []KeyValueExists{{KeyValue: KeyValue{Key: []byte("key")}, Exists: true}})
 	c, err = ts.Persist()
 	checkBatch(t, ts, nil, nil)
 	assert.Equal(t, nil, err)
@@ -78,7 +83,7 @@ func testMemCachedStorePersist(t *testing.T, ps Store) {
 	assert.Equal(t, []byte("value2"), v)
 }
 
-func checkBatch(t *testing.T, ts *MemCachedStore, put []KeyValue, del []KeyValue) {
+func checkBatch(t *testing.T, ts *MemCachedStore, put []KeyValueExists, del []KeyValueExists) {
 	b := ts.GetBatch()
 	assert.Equal(t, len(put), len(b.Put), "wrong number of put elements in a batch")
 	assert.Equal(t, len(del), len(b.Deleted), "wrong number of deleted elements in a batch")
@@ -174,7 +179,82 @@ func TestCachedSeek(t *testing.T) {
 	}
 }
 
-func newMemCachedStoreForTesting(t *testing.T) Store {
+func benchmarkCachedSeek(t *testing.B, ps Store, psElementsCount, tsElementsCount int) {
+	var (
+		searchPrefix      = []byte{1}
+		badPrefix         = []byte{2}
+		lowerPrefixGood   = append(searchPrefix, 1)
+		lowerPrefixBad    = append(badPrefix, 1)
+		deletedPrefixGood = append(searchPrefix, 2)
+		deletedPrefixBad  = append(badPrefix, 2)
+		updatedPrefixGood = append(searchPrefix, 3)
+		updatedPrefixBad  = append(badPrefix, 3)
+
+		ts = NewMemCachedStore(ps)
+	)
+	for i := 0; i < psElementsCount; i++ {
+		// lower KVs with matching prefix that should be found
+		require.NoError(t, ps.Put(append(lowerPrefixGood, random.Bytes(10)...), []byte("value")))
+		// lower KVs with non-matching prefix that shouldn't be found
+		require.NoError(t, ps.Put(append(lowerPrefixBad, random.Bytes(10)...), []byte("value")))
+
+		// deleted KVs with matching prefix that shouldn't be found
+		key := append(deletedPrefixGood, random.Bytes(10)...)
+		require.NoError(t, ps.Put(key, []byte("deleted")))
+		if i < tsElementsCount {
+			require.NoError(t, ts.Delete(key))
+		}
+		// deleted KVs with non-matching prefix that shouldn't be found
+		key = append(deletedPrefixBad, random.Bytes(10)...)
+		require.NoError(t, ps.Put(key, []byte("deleted")))
+		if i < tsElementsCount {
+			require.NoError(t, ts.Delete(key))
+		}
+
+		// updated KVs with matching prefix that should be found
+		key = append(updatedPrefixGood, random.Bytes(10)...)
+		require.NoError(t, ps.Put(key, []byte("stub")))
+		if i < tsElementsCount {
+			require.NoError(t, ts.Put(key, []byte("updated")))
+		}
+		// updated KVs with non-matching prefix that shouldn't be found
+		key = append(updatedPrefixBad, random.Bytes(10)...)
+		require.NoError(t, ps.Put(key, []byte("stub")))
+		if i < tsElementsCount {
+			require.NoError(t, ts.Put(key, []byte("updated")))
+		}
+	}
+
+	t.ReportAllocs()
+	t.ResetTimer()
+	for n := 0; n < t.N; n++ {
+		ts.Seek(searchPrefix, func(k, v []byte) {})
+	}
+	t.StopTimer()
+}
+
+func BenchmarkCachedSeek(t *testing.B) {
+	var stores = map[string]func(testing.TB) Store{
+		"MemPS": func(t testing.TB) Store {
+			return NewMemoryStore()
+		},
+		"BoltPS":  newBoltStoreForTesting,
+		"LevelPS": newLevelDBForTesting,
+	}
+	for psName, newPS := range stores {
+		for psCount := 100; psCount <= 10000; psCount *= 10 {
+			for tsCount := 10; tsCount <= psCount; tsCount *= 10 {
+				t.Run(fmt.Sprintf("%s_%dTSItems_%dPSItems", psName, tsCount, psCount), func(t *testing.B) {
+					ps := newPS(t)
+					benchmarkCachedSeek(t, ps, psCount, tsCount)
+					ps.Close()
+				})
+			}
+		}
+	}
+}
+
+func newMemCachedStoreForTesting(t testing.TB) Store {
 	return NewMemCachedStore(NewMemoryStore())
 }
 
@@ -242,3 +322,52 @@ func TestMemCachedPersistFailing(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, b1, res)
 }
+
+func TestCachedSeekSorting(t *testing.T) {
+	var (
+		// Given this prefix...
+		goodPrefix = []byte{1}
+		// these pairs should be found...
+		lowerKVs = []kvSeen{
+			{[]byte{1, 2, 3}, []byte("bra"), false},
+			{[]byte{1, 2, 5}, []byte("bar"), false},
+			{[]byte{1, 3, 3}, []byte("bra"), false},
+			{[]byte{1, 3, 5}, []byte("bra"), false},
+		}
+		// and these should be not.
+		deletedKVs = []kvSeen{
+			{[]byte{1, 7, 3}, []byte("pow"), false},
+			{[]byte{1, 7, 4}, []byte("qaz"), false},
+		}
+		// and these should be not.
+		updatedKVs = []kvSeen{
+			{[]byte{1, 2, 4}, []byte("zaq"), false},
+			{[]byte{1, 2, 6}, []byte("zaq"), false},
+			{[]byte{1, 3, 2}, []byte("wop"), false},
+			{[]byte{1, 3, 4}, []byte("zaq"), false},
+		}
+		ps = NewMemoryStore()
+		ts = NewMemCachedStore(ps)
+	)
+	for _, v := range lowerKVs {
+		require.NoError(t, ps.Put(v.key, v.val))
+	}
+	for _, v := range deletedKVs {
+		require.NoError(t, ps.Put(v.key, v.val))
+		require.NoError(t, ts.Delete(v.key))
+	}
+	for _, v := range updatedKVs {
+		require.NoError(t, ps.Put(v.key, []byte("stub")))
+		require.NoError(t, ts.Put(v.key, v.val))
+	}
+	var foundKVs []kvSeen
+	ts.Seek(goodPrefix, func(k, v []byte) {
+		foundKVs = append(foundKVs, kvSeen{key: slice.Copy(k), val: slice.Copy(v)})
+	})
+	assert.Equal(t, len(foundKVs), len(lowerKVs)+len(updatedKVs))
+	expected := append(lowerKVs, updatedKVs...)
+	sort.Slice(expected, func(i, j int) bool {
+		return bytes.Compare(expected[i].key, expected[j].key) < 0
+	})
+	require.Equal(t, expected, foundKVs)
+}
diff --git a/pkg/core/storage/memory_store.go b/pkg/core/storage/memory_store.go
index 45c4ae9fd..21ca47645 100644
--- a/pkg/core/storage/memory_store.go
+++ b/pkg/core/storage/memory_store.go
@@ -1,6 +1,8 @@
 package storage
 
 import (
+	"bytes"
+	"sort"
 	"strings"
 	"sync"
 
@@ -128,11 +130,21 @@ func (s *MemoryStore) SeekAll(key []byte, f func(k, v []byte)) {
 // seek is an internal unlocked implementation of Seek.
 func (s *MemoryStore) seek(key []byte, f func(k, v []byte)) {
 	sk := string(key)
+	var memList []KeyValue
 	for k, v := range s.mem {
 		if strings.HasPrefix(k, sk) {
-			f([]byte(k), v)
+			memList = append(memList, KeyValue{
+				Key:   []byte(k),
+				Value: v,
+			})
 		}
 	}
+	sort.Slice(memList, func(i, j int) bool {
+		return bytes.Compare(memList[i].Key, memList[j].Key) < 0
+	})
+	for _, kv := range memList {
+		f(kv.Key, kv.Value)
+	}
 }
 
 // Batch implements the Batch interface and returns a compatible Batch.
diff --git a/pkg/core/storage/memory_store_test.go b/pkg/core/storage/memory_store_test.go
index 259dbae68..6bb7d7526 100644
--- a/pkg/core/storage/memory_store_test.go
+++ b/pkg/core/storage/memory_store_test.go
@@ -1,9 +1,35 @@
 package storage
 
 import (
+	"fmt"
 	"testing"
+
+	"github.com/nspcc-dev/neo-go/internal/random"
+	"github.com/stretchr/testify/require"
 )
 
-func newMemoryStoreForTesting(t *testing.T) Store {
+func newMemoryStoreForTesting(t testing.TB) Store {
 	return NewMemoryStore()
 }
+
+func BenchmarkMemorySeek(t *testing.B) {
+	for count := 10; count <= 10000; count *= 10 {
+		t.Run(fmt.Sprintf("%dElements", count), func(t *testing.B) {
+			ms := NewMemoryStore()
+			var (
+				searchPrefix = []byte{1}
+				badPrefix    = []byte{2}
+			)
+			for i := 0; i < count; i++ {
+				require.NoError(t, ms.Put(append(searchPrefix, random.Bytes(10)...), random.Bytes(10)))
+				require.NoError(t, ms.Put(append(badPrefix, random.Bytes(10)...), random.Bytes(10)))
+			}
+
+			t.ReportAllocs()
+			t.ResetTimer()
+			for n := 0; n < t.N; n++ {
+				ms.Seek(searchPrefix, func(k, v []byte) {})
+			}
+		})
+	}
+}
diff --git a/pkg/core/storage/redis_store_test.go b/pkg/core/storage/redis_store_test.go
index d5613303b..f18aca684 100644
--- a/pkg/core/storage/redis_store_test.go
+++ b/pkg/core/storage/redis_store_test.go
@@ -12,7 +12,7 @@ type mockedRedisStore struct {
 	mini *miniredis.Miniredis
 }
 
-func prepareRedisMock(t *testing.T) (*miniredis.Miniredis, *RedisStore) {
+func prepareRedisMock(t testing.TB) (*miniredis.Miniredis, *RedisStore) {
 	miniRedis, err := miniredis.Run()
 	require.Nil(t, err, "MiniRedis mock creation error")
 
@@ -37,7 +37,7 @@ func (mrs *mockedRedisStore) Close() error {
 	return err
 }
 
-func newRedisStoreForTesting(t *testing.T) Store {
+func newRedisStoreForTesting(t testing.TB) Store {
 	mock, rs := prepareRedisMock(t)
 	mrs := &mockedRedisStore{RedisStore: *rs, mini: mock}
 	return mrs
diff --git a/pkg/core/storage/store.go b/pkg/core/storage/store.go
index bd62f6001..f87f94e87 100644
--- a/pkg/core/storage/store.go
+++ b/pkg/core/storage/store.go
@@ -55,7 +55,8 @@ type (
 		// PutChangeSet allows to push prepared changeset to the Store.
 		PutChangeSet(puts map[string][]byte, dels map[string]bool) error
 		// Seek can guarantee that provided key (k) and value (v) are the only valid until the next call to f.
-		// Key and value slices should not be modified.
+		// Key and value slices should not be modified. Seek can guarantee that key-value items are sorted by
+		// key in ascending way.
 		Seek(k []byte, f func(k, v []byte))
 		Close() error
 	}
diff --git a/pkg/core/storage/storeandbatch_test.go b/pkg/core/storage/storeandbatch_test.go
index 022d83adb..70a3787ea 100644
--- a/pkg/core/storage/storeandbatch_test.go
+++ b/pkg/core/storage/storeandbatch_test.go
@@ -19,7 +19,7 @@ type kvSeen struct {
 
 type dbSetup struct {
 	name   string
-	create func(*testing.T) Store
+	create func(testing.TB) Store
 }
 
 type dbTestFunction func(*testing.T, Store)
diff --git a/pkg/rpc/response/result/invoke.go b/pkg/rpc/response/result/invoke.go
index 83685a7ac..ebd7b699c 100644
--- a/pkg/rpc/response/result/invoke.go
+++ b/pkg/rpc/response/result/invoke.go
@@ -20,10 +20,11 @@ type Invoke struct {
 	FaultException         string
 	Transaction            *transaction.Transaction
 	maxIteratorResultItems int
+	finalize               func()
 }
 
 // NewInvoke returns new Invoke structure with the given fields set.
-func NewInvoke(vm *vm.VM, script []byte, faultException string, maxIteratorResultItems int) *Invoke {
+func NewInvoke(vm *vm.VM, finalize func(), script []byte, faultException string, maxIteratorResultItems int) *Invoke {
 	return &Invoke{
 		State:                  vm.State().String(),
 		GasConsumed:            vm.GasConsumed(),
@@ -31,6 +32,7 @@ func NewInvoke(vm *vm.VM, script []byte, faultException string, maxIteratorResul
 		Stack:                  vm.Estack().ToArray(),
 		FaultException:         faultException,
 		maxIteratorResultItems: maxIteratorResultItems,
+		finalize:               finalize,
 	}
 }
 
@@ -55,8 +57,17 @@ type Iterator struct {
 	Truncated bool
 }
 
+// Finalize releases resources occupied by Iterators created at the script invocation.
+// This method will be called automatically on Invoke marshalling.
+func (r *Invoke) Finalize() {
+	if r.finalize != nil {
+		r.finalize()
+	}
+}
+
 // MarshalJSON implements json.Marshaler.
 func (r Invoke) MarshalJSON() ([]byte, error) {
+	defer r.Finalize()
 	var st json.RawMessage
 	arr := make([]json.RawMessage, len(r.Stack))
 	for i := range arr {
diff --git a/pkg/rpc/server/client_test.go b/pkg/rpc/server/client_test.go
index 4bff819b0..cd3b3a291 100644
--- a/pkg/rpc/server/client_test.go
+++ b/pkg/rpc/server/client_test.go
@@ -714,7 +714,7 @@ func TestCreateNEP17TransferTx(t *testing.T) {
 	require.NoError(t, err)
 	require.NoError(t, acc.SignTx(testchain.Network(), tx))
 	require.NoError(t, chain.VerifyTx(tx))
-	v := chain.GetTestVM(trigger.Application, tx, nil)
+	v, _ := chain.GetTestVM(trigger.Application, tx, nil)
 	v.LoadScriptWithFlags(tx.Script, callflag.All)
 	require.NoError(t, v.Run())
 }
diff --git a/pkg/rpc/server/server.go b/pkg/rpc/server/server.go
index fe7c06487..051dda712 100644
--- a/pkg/rpc/server/server.go
+++ b/pkg/rpc/server/server.go
@@ -624,6 +624,7 @@ func (s *Server) calculateNetworkFee(reqParams request.Params) (interface{}, *re
 			if respErr != nil {
 				return 0, respErr
 			}
+			res.Finalize()
 			if res.State != "HALT" {
 				cause := fmt.Errorf("invalid VM state %s due to an error: %s", res.State, res.FaultException)
 				return 0, response.NewRPCError(verificationErr, cause.Error(), cause)
@@ -742,7 +743,8 @@ func (s *Server) getNEP17Balance(h util.Uint160, acc util.Uint160, bw *io.BufBin
 	}
 	script := bw.Bytes()
 	tx := &transaction.Transaction{Script: script}
-	v := s.chain.GetTestVM(trigger.Application, tx, nil)
+	v, finalize := s.chain.GetTestVM(trigger.Application, tx, nil)
+	defer finalize()
 	v.GasLimit = core.HeaderVerificationGasLimit
 	v.LoadScriptWithFlags(script, callflag.All)
 	err := v.Run()
@@ -1490,7 +1492,6 @@ func (s *Server) invokeContractVerify(reqParams request.Params) (interface{}, *r
 		tx.Signers = []transaction.Signer{{Account: scriptHash}}
 		tx.Scripts = []transaction.Witness{{InvocationScript: invocationScript, VerificationScript: []byte{}}}
 	}
-
 	return s.runScriptInVM(trigger.Verification, invocationScript, scriptHash, tx)
 }
 
@@ -1511,7 +1512,7 @@ func (s *Server) runScriptInVM(t trigger.Type, script []byte, contractScriptHash
 	}
 	b.Timestamp = hdr.Timestamp + uint64(s.chain.GetConfig().SecondsPerBlock*int(time.Second/time.Millisecond))
 
-	vm := s.chain.GetTestVM(t, tx, b)
+	vm, finalize := s.chain.GetTestVM(t, tx, b)
 	vm.GasLimit = int64(s.config.MaxGasInvoke)
 	if t == trigger.Verification {
 		// We need this special case because witnesses verification is not the simple System.Contract.Call,
@@ -1539,7 +1540,7 @@ func (s *Server) runScriptInVM(t trigger.Type, script []byte, contractScriptHash
 	if err != nil {
 		faultException = err.Error()
 	}
-	return result.NewInvoke(vm, script, faultException, s.config.MaxIteratorResultItems), nil
+	return result.NewInvoke(vm, finalize, script, faultException, s.config.MaxIteratorResultItems), nil
 }
 
 // submitBlock broadcasts a raw block over the NEO network.
diff --git a/pkg/services/oracle/response.go b/pkg/services/oracle/response.go
index 6b5f9d541..38a69550e 100644
--- a/pkg/services/oracle/response.go
+++ b/pkg/services/oracle/response.go
@@ -134,16 +134,17 @@ func (o *Oracle) CreateResponseTx(gasForResponse int64, vub uint32, resp *transa
 }
 
 func (o *Oracle) testVerify(tx *transaction.Transaction) (int64, bool) {
-	v := o.Chain.GetTestVM(trigger.Verification, tx, nil)
+	v, finalize := o.Chain.GetTestVM(trigger.Verification, tx, nil)
 	v.GasLimit = o.Chain.GetPolicer().GetMaxVerificationGAS()
 	v.LoadScriptWithHash(o.oracleScript, o.oracleHash, callflag.ReadOnly)
 	v.Jump(v.Context(), o.verifyOffset)
 
-	ok := isVerifyOk(v)
+	ok := isVerifyOk(v, finalize)
 	return v.GasConsumed(), ok
 }
 
-func isVerifyOk(v *vm.VM) bool {
+func isVerifyOk(v *vm.VM, finalize func()) bool {
+	defer finalize()
 	if err := v.Run(); err != nil {
 		return false
 	}