I've recently upgraded to 13.04 from 12.04 and I've experienced some performance issues with games (mostly) I wasn't having with 12.04, relatively simple games like xonotic freeze my system after an hour or so and I have to force shut down the system.
Specs:
Inter I7 2.2 GHz 4Gb ram GeForce GT 540M
I've tried running the games with primusrun, optirun and without them, all the same result. If I try to run them in the lxde desktop I get slightly less problems, but the desktop itself is presenting a lot of bugs and programs constantly freeze.
Maybe you've got an overheating issue, possibly caused by dust and debris clogging up the aluminum cooling fins around the fan(s). You can search for any answers having the word Psensor in them if you want to find out more about how to monitor your hardware temperatures. I don't think that overheating is your problem though, because it often causes crashing and your problem is freezing.
What does often cause freezing is a failing graphics card. If your computer has a graphics card and you are fortunate enough to have a spare graphics card that you can temporarily swap with your GeForce GT 540M, then you can test this possibility for yourself.
If neither of these two possibilities proves to be the cause of your performance issues, then at least you will have narrowed down the range of possible causes of your performance issues. What would help you in this case is to take a look at the answers to What should I do when Ubuntu freezes?.
Have you tried using both
nvidia-current-updatesand themesa-utilspackages?To install Nvidia drivers, use the following at the terminal:
sudo apt-get install nvidia-current-updatesTo remove all Nvidia drivers and install mesa-utils:
sudo apt-get remove nvidia-current nvidia-graphics-driverssudo apt-get purge nvidia*sudo apt-get install mesa-utils