The speed of copying (which is done regulary for e.g. subnet changes)
is less, however it isn't on the hot path and the absolute time
difference is insignificant.
```
name old time/op new time/op delta
NodeAttributes-8 96.2ns ± 1% 158.3ns ± 1% +64.61% (p=0.000 n=10+10)
name old alloc/op new alloc/op delta
NodeAttributes-8 32.0B ± 0% 32.0B ± 0% ~ (all equal)
name old allocs/op new allocs/op delta
NodeAttributes-8 2.00 ± 0% 2.00 ± 0% ~ (all equal)
```
Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>
