This issue first appeared when playing native Team Fortress 2 (on highest settings). The game runs with very good frame rate of 200 FPS+ until after a varying amount of map changes it will drop to just about ~7 FPS right after the loading screen. This can be forced to happen by alt+tabbing out of full screen and playing a bit with desktop effects (or other things that potentially demand the GPU/vram, I assume).
Bug report in the TF2 issue tracker: https://github.com/ValveSoftware/steam-for-linux/issues/140
Today I noticed this also happens with the Unigine Heaven benchmark (http://unigine.com/products/heaven/).
Running the benchmark at the “Extreme” preset will result in normal behavior until the benchmark run ends and the world reloads, then the FPS are locked to ~7 FPS for the entire second run without change, not even in less demanding scenes.
Other Linux users with different distributions, desktop environments, etc. have also been able to reproduce this on their systems.
The nvidia-bug-report.log I took contains nothing but the uname. I don’t know how to enable debug logging as my distribution doesn’t support use of the “startx” command.
EDIT: Got tipped off by another one affected by this that AA seems to be an issue. Running the benchmark or TF2 without AA seems to prevent this from happening on both our systems.