Comment 10 for bug 1893969

I have other problems that I assume are related but may not be the same bug, so I did not report them here; for the record (in case it helps), they include:

* OBS will not repaint its preview window _at all_ and sometimes hangs UNLESS I move it to my leftmost display (DP-2-1) _and resize it_. After doing this, it is reliable and works normally on ANY display. If I don't do this, it doesn't repaint at all on any display. The UI works fine, but the video overlay (via whatever method it uses) for the preview window just shows a gray box that sometimes takes on corruption.

* Electron apps run fine on DP-2-1 and DP-2-8, but if I move them to eDP-1 (located at the far right, the only unscaled panel running 3840x2160) they are _extremely_ slow to draw. Typing in the window, the characters take up to several seconds to show up on screen, and clicks take seconds to register. This is visible in Slack, Discord, Keybase, and Element. Disabling GPU acceleration (either via the app preference in Slack, or the Electron option --disable-gpu for others) causes them to run normally, with no lag.

* OpenGL applications _in general_ run terribly on eDP-1; with vblank_mode=0, maximized glxgears runs over 400 fps on DP-2-1 and DP-2-8, but under 100 on eDP-1. I have seen it run as few as ~15 FPS on eDP-1 but am not seeing that currently; that may be related to other factors?

* Video playback is noticeably jerky sometimes, appearing to skip or jitter frames. I have not noticed whether it matters which display I am using when this happens. Sometimes I don't notice it, sometimes it seems pretty bad. This is visible using mplayer or watching YouTube in Firefox. This is a subjective point, I cannot _measure_ the frame drops (or at least, I don't know how).