Bug 472066

Summary: Frames dropped and heavy stuttering when compositing enabled
Product: [Plasma] kwin Reporter: herrcrazi <herrcrazi>
Component: generalAssignee: KWin default assignee <kwin-bugs-null>
Status: RESOLVED FIXED    
Severity: major CC: herrcrazi, nate
Priority: NOR    
Version First Reported In: 5.27.7   
Target Milestone: ---   
Platform: Arch Linux   
OS: Linux   
Latest Commit: Version Fixed/Implemented In: 6.0
Sentry Crash Report:
Attachments: system specs (inxi)
kwin support info

Description herrcrazi 2023-07-08 08:35:43 UTC 
Created attachment 160164 [details]
system specs (inxi)

Aloha !

KWin appears to cause dropped frames and heavy stuttering in games or graphical applications such as video players, OBS, Blender, etc, whenever compositing is enabled. This behavior disappears when compositing is disabled.

Games ran while compositing is enabled suffer from a significant drop in FPS and heavy stuttering. Movements appears not smooth, as if every few frames were dropped or swapped. This is also visible by using gltest (https://git.ralfj.de/gltest.git), altho the system needs to be somewhat loaded to really exhibit the issue.

I have tried disabling KWin's vsync by setting the following :
KWIN_X11_REFRESH_RATE=144000
KWIN_X11_NO_SYNC_TO_VBLANK=1
KWIN_X11_FORCE_SOFTWARE_VSYNC=1

This, however, did not solve the problem.
Comment 1 herrcrazi 2023-07-08 08:38:55 UTC 
Created attachment 160193 [details]
kwin support info
Comment 2 Nate Graham 2023-09-12 20:56:32 UTC 
This has been a major focus area in Plasma 6 and it should be substantially improved, if not completely fixed.