I have this problem where programs that use OpenGL, like Plasma Desktop or my own Qt Quick 2 based program slows X to a crawl with the mouse cursor lagging over the screen when moved.
It only happens like every 3-5 times an OpenGL program is started and it only happens as the program starts.
The workaround is switching to VT and back, which restores normal X speed but crashes the OpenGL program.
Installed is a 770 GTX with 3 screens and an Oculus Rift connected and a 570 GTX that has no screens connected.
[url]https://brix-verden.dk/misc/nvidia-bug-report.log.gz[/url]