CPU usage shoots up to 90-98% sometimes while playing

[Squa11_Leonhart]

I have an i5 3570k and haven't experienced any slowdown, except when Norton starts doing stuff while I'm playing. Even then it's only brief lasting about 2 seconds. See if your antivirus is messing with performance. I haven't messed with occlusion culling but I think you can get to it via sys. tools.

occlusion culling is a setting in the games graphics settings......