Yesterday i've noticed that game updated itself. Before update i could play on high with ~40fps, now it's 30~20FPS and also i have freezes and major slowdowns (form 40 to 20 for a sec and then back to 40 - doesn't matter if i drive slow or fast) When switched to LOW - i'm getting like 60 FPS, but still freezes remains - gameplay totally stops for about one second
That update should have done nothing more than restore any modified default files. Not sure why it would give you a worse framerate.