FaceIt AC causing mouse lag (droping sensitivity)/fps drop

Hello.
My fps drops when I move my mouse and its been the whole time I play on faceit.
It looks exactly like on this video https://www.youtube.com/watch?v=9SR8s6HnATs
but for me its droping from 700 to 200-100. Or 400-300 when I reboot right before the game
i9700
970gtx
When I turn ac off. everything is awesome
No viruses, no software , Clean pc with steam , cs, faceit .
I was doing some research for a long time and nothing helps.