Logged on today and felt my eyes jittering as I was moving around. Been playing 20 years so I knew instantly something didn’t look right. I noticed my FPS was jumping between 90-120 over n over which is not right i should always have 120 consistently on my setup.
I started messing with the setting & discovered that multithread rendering at the bottom of the Graphics options was causing the issue. I disabled it and instantly back to being 120FPS constantly & the jittering of my game went away.
So if your game looks like its lagging try disabling it.