The problem was in game, not in my computer. Let's explain:
12.a - version on school PC
12.b - version I playes while I posted this (broken)
12.c - the new version released today (works good)

So there was something with game code what slowed me on high speeds

Topic to close

Hello!
I usually play Factorio on my PC, but some days ago I installed it on school PC. Adn I noticed something strange - on school computer (which theoritically is much weaker than mine) game runs smooth even on 128x speed (I'm using edited SpeedButtons).

Specs:
My PC: Win10 Home x64, Pentium ...