Read about this technology. It's in many games, even on consoles but PhysX enabled games are showing their full peformance with NVIDIA GPU's (9600 and higher +8600, 8700, 8800). In your case PhysX is used on your CPU not GPU and is affecting your performance or you are using only few features from that technology (like some games from consoles) or physx doesn't work at all
ps. I saw a guy on youtube playing Batman AA on single radeon 48xx and c2d with full physx enabled - he got only 30+ fps and sometimes even lower than 30.
This post has been edited by mando: 26 January 2010 - 01:44 PM