stutters when switching focus if second monitor is fullscreened

[michaelBelsanti]

This is most obvious when a video is playing fullscreen on my second monitor. Any change in window focus or workspace switch on my primary monitor will cause the entire desktop to stutter for a split second.

This issue does not occur when the monitors are reversed, ie a fullscreen video on my primary display and switching focus on the other display.

The only error output I have noticed is this:
Feb 07 15:57:06 hades .cosmic-comp-wrapped[2438]: [GL] GL_INVALID_VALUE in glTexSubImage2D(xoffset 0 + width 990 > 988)
It sometimes outputs during one of the stutters, but not for all of them.

System Info:
OS: NixOS
cosmic-comp rev a3714b0
GPU: AMD Radeon RX 7800 XT
Mesa: Mesa 24.3.4
Kernel: 6.13.1-cachyos

Primary display: 1920x1080, 240hz, VRR
Second display: 1920x1080, 60hz

Please let me know if any additional system information or logs would be helpful

[feikedonia]

I can't reproduce this issue on my hardware...

System Info
Fedora 40
cosmic-comp-1.0.0~alpha.5.1^git20250128.63995c4-1.fc40.x86_64
GPU: intel
CPU: 11th Gen Intel(R) Core(TM) i7-1165G7 @ 2.80GHz
Kernel: 6.12.11-100.fc40.x86_64
Laptop, with external display which is an older square monitor, which I use with an hdmi-vga converter to work with.

I tried fullscreen on the VGA square external monitor and then changed focus with Super + arrows and Super + Shift + arrows; I also did the reverse, as you described.

((BTW, I don't have changed any VRR settings, so they are on the default settings)))

[Drakulix]

@michaelBelsanti Does this issue occur if VRR is set to disabled for your primary display in cosmic-settings?

[michaelBelsanti]

Yes it does. It stops happening if I lower the refresh rate on my primary display to 60hz. It also seems less severe the closer the refresh rate gets to 60.

[michaelBelsanti]

This issue is gone using the latest nixos-cosmic revision, as well as the GL_INVALID_VALUE log messages.