10 fps in which application? in which resolution? What is your CPU?
Any hints in /var/log/XFree86.0.log?
Have you set strange things like AA and frame sync in nvidia-settings?
With everything forced on and max settings, P4-3000 and GF5700 I get 75fps
normal win and 18 fps at 1280x1024 maximized in glxgears.
Sönke