I just bought the game a few days ago, and I am taking the SinglePlayer very slowly while enjoying every second of it, though it's hard to enjoy some parts when my sound stutters and the game runs slow (sounds and feels like a slo-mo Matrix scene). This happens only in a few spots on larger maps while my FPS is still solid in the 30-40s (scoping into smoke, walking in random halls, etc). I already updated my sound drivers, lowered hardware acceleration to the lowest/second lowest, and I even tried lowering sound quality (which sounds like crap and doesn't help any). If anyone can help me, it's much appreciated. Also, did any of the game patches address this issue? I didn't bother patching the game because I'm not too fond of CoD style MP.
Athlon XP 2400+
1.25 GB RAM
ATi X800GT (overclocked)
Creative SB! Live
I play on all high/extra settings without shadows.