Generally we'd seen significant improvements with xcompmgr. There were a few discussions on scheduling, as the window composition stage is using also the 3D hardware, therefore your GL app has slightly less resource to do what it wants, but I hadn't previously noted a significant difference. So far...

PeterO wrote: ↑

Mon Jul 01, 2019 5:26 pm

glxgears still only managing 40 fps in a full screen window.
But
Tearing on vertical lines in my demo code is gone
PeterO

Disable the compositor with the A8 option of raspi-config...

Here 60fps with glxgears running in 2 screens at 1920x1080