Same issue here. 8600k gtx 1080 16 GB ram. After 20-45 mins i start to get noticeable stutter or choppiness especially when looking around fast. driving me nuts. i cant enjoy the game because i spend hours tweaking random things on my PC that shouldn't need to be tweaked to try and get these issues away. Dont know what triggers it and time always varies. If i mess with video settings it seems to make it happen as well. Any temp fixes?