Could our low frame rate issue be cause by NPC's using PHYSX? i know it might be a long shot but i thought i'd mention it. Since the issues seem to be from nvidia users and only nvidia users can use PHYSX.

Nope.

I had the same issue with my AMD card. I fixed it with the dll trick mentioned on another thread.

That (initial) response was somewhat brief. I believe it to be accurate, but I also believe that you need to know more about PhysX than the mistaken ideas you now have concerning it.

Before nVIDIA bought the company out, PhysX was competing with Havok as a CPU-based software for handling the physics elements in games. A year or two before nVIDIA acquired the company, they released a dedicated procseeor on an add-on circuit board to improve the performance of the games using PhysX.

They had continued leasing their CPU-based software to game developers after beginning to produce their hardware device. nVIDIA has continued to lease the PhysX software for CPUs to game developers. That software has no requirement for the special capabilities now included in some Geforce video graphics cards. Bioware uses PhysX instead of Havok, and Radeons work fine with Dragon Age and Mass Effect. Bethesda uses Havok, if they use any physics software . .

Yeah it's havok, says it on the load screen. Physx still works best with a seperate card, doesn't benefit if the graphics card is being stressed in supported games. Conspiracy theorists like to say that all the physics software on the market (bullet I think is the other big one) would run better if optimized for SSE4+

The problem with that is you can't assume they have SSE4+.

You can build it to fallback, but that can be tricky...