I have Ubuntu 12.10 an nvidia 540M graphic card with optimis technology. If I install the nvidia current package from Software Center (and bumblebee for optimus) when I run 'optirun glxspheres' i get 120-140 frames per second.
If I install the nvidia current driver from 'Additional Drivers', and run 'optirun glxspheres' i get 170-190 fps, but glxspheres and all the games I play always start full screen. And this is a problem because some games mess up my desktop resolution and I have to relog to fix it every time I exit a game. So I can't use this driver.
Also if I uninstall the driver from additional drivers and go back to the one in software center I still get 170+ fps and games still start full screen. It's like installing that driver also modifies some configurations or something.
The same thing happens in Ubuntu 12.04. So, the question is:
Why do all the apps that use the GPU start full screen after I install the nvidia driver from 'additional drivers' and why do I get lower FPS with the driver from 'software center'?