Step on the gas!
Maybe mesa was installed or updated after nvidia-glx / driver package?
Many games will run 100% cpu (q3a, rtcw, etc). but if you have really bad FPS, it could be that Mesa's libGL is being used instead of nvidia's.
If that's the case, or you are unsure, you can try to re-install the GL libraries.
I use debian, so I can just put mesa packages on hold and not have to worry about updates fiddling with my libGL, but suse or other distros may not have such an option.