Bug 506615

Summary:	Cursor drops frames, UI is janky on Wayland
Product:	[Plasma] kwin	Reporter:	Random Jerk <randomjerk2012>
Component:	core	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED FIXED
Severity:	normal
Priority:	NOR
Version First Reported In:	6.4.2
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Random Jerk 2025-07-05 05:17:07 UTC

***
If you're not sure this is actually a bug, instead post about it at https://discuss.kde.org

If you're reporting a crash, attach a backtrace with debug symbols; see https://community.kde.org/Guidelines_and_HOWTOs/Debugging/How_to_create_useful_crash_reports

Please remove this comment after reading and before submitting - thanks!
***

SUMMARY
The KDE Wayland UI (since atleast 6.3.x and ongoing) is really janky, with the mouse cursor dropping frames all over. This happens on AMD 6800XT and 9070 GPUs.  Does not happen on Intel or Nvidia GPUs.

STEPS TO REPRODUCE
1. Login into Plasma session and start using it. The mouse cursor starts dropping frames every few seconds, no matter what app is running or not.


OBSERVED RESULT
Cursor drops frames, UI is janky on Wayland

EXPECTED RESULT
UI is expected to be smooth, no cursor frame drops. 

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
(available in the Info Center app, or by running `kinfo` in a terminal window)
Linux/KDE Plasma:  Linux KDE Plasma
KDE Plasma Version: 6.4.2
KDE Frameworks Version: 6.15.0
Qt Version: 6.9.1

ADDITIONAL INFORMATION
Tried both parameters KWIN_DRM_DELAY_VRR_CURSOR_UPDATES=1 and KWIN_FORCE_SW_CURSOR=1, and it did not solve the issue.

Comment 1 Random Jerk 2025-07-05 05:34:14 UTC

Details of my system

Operating System: CachyOS Linux 
KDE Plasma Version: 6.4.2
KDE Frameworks Version: 6.15.0
Qt Version: 6.9.1
Kernel Version: 6.15.4-4-cachyos (64-bit)
Graphics Platform: Wayland
Processors: 32 × AMD Ryzen 9 5950X 16-Core Processor
Memory: 64 GiB of RAM (62.7 GiB usable)
Graphics Processor: AMD Radeon RX 9070
Manufacturer: Gigabyte Technology Co., Ltd.
Product Name: X570 AORUS PRO WIFI
System Version: -CF

Comment 2 Vlad Zahorodnii 2025-07-08 09:23:19 UTC

Can you share your output settings? Did you enable VRR?

If you set KWIN_DRM_OVERRIDE_SAFETY_MARGIN envvar to 16000, does it improve anything?

Comment 3 Random Jerk 2025-07-12 15:15:18 UTC

(In reply to Vlad Zahorodnii from comment #2)
> Can you share your output settings? Did you enable VRR?
> 
> If you set KWIN_DRM_OVERRIDE_SAFETY_MARGIN envvar to 16000, does it improve
> anything?

Hello,

Yes, VRR is enabled. Can you elaborate on what you mean by output settings? 

In the last few days, the issue got fixed and not sure why. I added KWIN_DRM_DELAY_VRR_CURSOR_UPDATES=1 and used LACT to change the GPU Power Profile Mode to 3D_FULL_SCREEN. I dual boot CachyOS and Bazzite on the same hardware, and the above changes fixed the issue on both. Earlier, the issue occured on both OSes.

Comment 4 Random Jerk 2025-07-16 13:50:42 UTC

Closing the issue for now, as I'm not able to reproduce the issue.