I'm having similar problems, though I'm relating it to possible network latency issues (since connections are rough atm as is).
Vista Home Premium (SP1) 32-bit
Nvidia GeForce 8600M GT - 512MB Dedictated Memory
Since this laptop is a custom lenovo from ABS Pc, video drivers are a pain in the butt to get ahold of. The major issue I'm having is that the settings don't matter up or down. My reccomended defaults were relatively high, but even with settings set completely on low I might be lucky to pull 15 FPS. The bigger trouble is studder lag, which lets my demigod move for about 3 seconds and lag for about 5. Needless to say, before submitting bugs or getting more friends to help test with...I can't even play with success 
Tomorrow's new beta build helping in-game latency? I'm hoping its that and not the card
.