ssz.Root.equals performance

[twoeths]

Describe the bug

In the profiler result below, Root comparison and state.setStateCachesAsPersistent seems to be too high compared to others:

We need to analyse why and if we can improve it

Update

My other profiler shows that postState.setStateCachesAsPersistent(); is only 0.1ms (so we can iggnore it) while Root comparison is still that high (2.6ms)

[twoeths]

Benchmark for Root equals check:
Currently block.stateRoot is tree backed

test ssz equal                                                         17778.09 ops/s      56.24900 us/op 264549 runs    15.01 s

If I use block.stateRoot.valueOf() as Uint8Array it's 3.5 times faster:

test ssz equal using valueOf()                                         63673.99 ops/s      15.70500 us/op 933370 runs    15.03 s

seems like this is related to ChainSafe/ssz#83

also, we use ssz.Root.equals() in a lot of places, we need to either apply the pattern to all places or fix the above ssz issue.

Update

byteArrayEquals is the winner, it's 40x faster

test ssz equal using byteArrayEquals                                   708215.3 ops/s      1.412000 us/op 8278979 runs    15.47 s