VGA compatible controller: nVidia Corporation G96 [GeForce 9500 GT] (rev a1)
Intel(R) Core(TM)2 Quad CPU Q8200 @ 2.33GHz
I have the same problem on Debian Testing after a recent upgrade. The version of the nvidia driver I was using is this:
xserver-xorg-video-nvidia Version: 280.13.really.275.28-1
After downloading the binary driver from the nvidia website (NVIDIA-Linux-x86_64-285.05.09)
and uninstalling all of the debian nvidia stuff (apt-get remove nvidia-installer-cleanup),
It was better, but 2 more options to switch on in xorg.conf helped too, as per the suggestion here:
Option “RenderAccel” “on”
Option “UseEvents” “on”
End result: Things are a bit better, but I still end up seeing my whole desktop grind to a halt especially when running GTK+ based apps such as firefox, thunderbird, and openoffice.
The culprit is always xorg at 100%.
When this happens, I have to wait multiple seconds for a response to my keyboard or mouse clicks.
I disabled all desktop effects. I am using KDE by the way.