I recently switched to a GTX 960 with 4GB of RAM from an ATI card. I had been running the open source ATI drivers and I am now using the NVIDIA binaries.
The most interesting issue is resizing a terminal horizontally vs vertically. Vertically I can move my mouse very quickly before the cursor “loses” the edge of the window and it takes a second to catch up. Horizontally I can lose the edge of the terminal very easily. In Ubuntu 15.10 the terminal re-flows text as it resizes horizontally, so that is perhaps the issue - the minor increase in CPU usage gets in the way of the driver being able to respond quickly? With an application like Chrome displaying this page it just takes seconds to get a refresh - really very bad.
When I click on a window to bring it to the front nothing happens for anything from a fraction of a second up to several seconds. It seems to be quite random. Changing the CPU and GPU DVFS settings and various compiz and quality settings seems to make no difference. Changing between a single and triple head set up doesn’t help either.
This same machine, same installation with the ATI card and FOSS drivers worked just fine and the new GPU is much more powerful, so it seems to be a driver issue.
Dragging windows around is perfect and something like switching tabs in chrome is fine, so it seems to be an X or compiz related issue.
nvidia-bug-report.log.gz (93.6 KB)