Only 7 months late
but at least its almost fixed!! With the latest beta 304.48 drivers which also install a newer PhysX version with DX11 max everything + physx is now reporting 44 avg FPS in the benchmark & ingame all the challenges I tried were very smooth not perfect but about 95% smooth some very minor microstuttering now & again.
This is on a single GTX580 @ 1920x1200 + FXAA & every single setting maxxed out.
http://www.geforce.com/whats-new/articles/nvidia-geforce-304-48-beta-drivers-released/
DX11 + max everything on its own with no physx is slightly quicker still but only 5FPS on average.

This is on a single GTX580 @ 1920x1200 + FXAA & every single setting maxxed out.
http://www.geforce.com/whats-new/articles/nvidia-geforce-304-48-beta-drivers-released/
DX11 + max everything on its own with no physx is slightly quicker still but only 5FPS on average.