Penumbre Lag when turning WTF

[venge]

I'm having this exact same problem, and theres no reason for it, my computer is well above the requirements and should play overture with ease and it does. until i turn with the mouse, then it freezes up or goes really slow like to 5fps. im thinking it might have something to do with textures? has anyone found a fix for this issue.
oh and i have turned every setting as low as possible, still have the same issue, which is ridiculous for my laptop.