diff --git a/netmap/netmap.go b/netmap/netmap.go
index f0ece7d..85e2a84 100644
--- a/netmap/netmap.go
+++ b/netmap/netmap.go
@@ -113,9 +113,10 @@ func (n nodes) Hash() uint64 {
 	return 0
 }
 
-// weights returns slice of nodes weights W.
-func (n nodes) weights(wf weightFunc) []float64 {
-	w := make([]float64, 0, len(n))
+func (n nodes) appendWeightsTo(wf weightFunc, w []float64) []float64 {
+	if cap(w) < len(n) {
+		w = make([]float64, 0, len(n))
+	}
 	for i := range n {
 		w = append(w, wf(n[i]))
 	}
@@ -149,10 +150,13 @@ func (m NetMap) PlacementVectors(vectors [][]NodeInfo, pivot []byte) ([][]NodeIn
 	wf := defaultWeightFunc(m.nodes)
 	result := make([][]NodeInfo, len(vectors))
 
+	var ws []float64
+
 	for i := range vectors {
 		result[i] = make([]NodeInfo, len(vectors[i]))
 		copy(result[i], vectors[i])
-		hrw.SortHasherSliceByWeightValue(result[i], nodes(result[i]).weights(wf), h)
+		ws = nodes(result[i]).appendWeightsTo(wf, ws[:0])
+		hrw.SortHasherSliceByWeightValue(result[i], ws, h)
 	}
 
 	return result, nil
diff --git a/netmap/selector.go b/netmap/selector.go
index b16e774..ab73cec 100644
--- a/netmap/selector.go
+++ b/netmap/selector.go
@@ -171,8 +171,10 @@ func (c *context) getSelectionBase(s netmap.Selector) []nodeAttrPair {
 	}
 
 	if len(c.hrwSeed) != 0 {
+		var ws []float64
 		for i := range result {
-			hrw.SortHasherSliceByWeightValue(result[i].nodes, result[i].nodes.weights(c.weightFunc), c.hrwSeedHash)
+			ws = result[i].nodes.appendWeightsTo(c.weightFunc, ws[:0])
+			hrw.SortHasherSliceByWeightValue(result[i].nodes, ws, c.hrwSeedHash)
 		}
 	}