i figured out what the problem with mine.while changing nvidia-curent to nvidia-current-udates ,instead of nvidia-current-updates i entered nvidia-current_updates.now i changed it and now its pulling 80 to 90 frames.

now i got question. even though i set wrong path in config file,it was giving 15 fps with optirun, with out that 2 r 3 fps.what was making it to pull 15 frames with out nvidia card set to work?