Finally! I have found what causes this huge performance drop
Disabling this option restores performance.
Details
Got my performance back. Now I’ll work on further optimization of the problems
Ivan3z found.
Turning off this retainerBox option in 5.4 gives a small boost.
Performance in both versions looks similar now but 5.5 consumes more memory and RHIT much faster
The only open question that remains is why this option causes such a big problem on 5.5
UPD Forgot to turn-on weapon list widget, so the performance with it is this, 5.5 consumes even more memory
