Bug 506038

Summary:	Applications slow down when moved to a off-screen virtual desktop
Product:	[Plasma] kwin	Reporter:	Patrick Auernig <patrick.auernig>
Component:	performance	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED FIXED
Severity:	normal	CC:	xaver.hugl
Priority:	NOR
Version First Reported In:	6.4.0
Target Milestone:	---
Platform:	NixOS
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Patrick Auernig 2025-06-23 11:29:54 UTC

SUMMARY
When moving an application to a different virtual desktop, applications appear to become heavily frame limited. This can most easily be observed with games.
I could so far reproduce this problem with a free idle game on Steam, a Bevy example game, and a YouTube video playing in Firefox.

STEPS TO REPRODUCE
1. Open an application that is known to have this problem
2. Move the application to an off-screen virtual desktop or switch to one
3. Open the overview (Meta+W) and notice that the preview has a very low frame rate

OBSERVED RESULT
Applications are being frame limited when off-screen

EXPECTED RESULT
Applications behave as normal, even when off-screen

SOFTWARE/OS VERSIONS
Operating System: NixOS 25.11
KDE Plasma Version: 6.4.0
KDE Frameworks Version: 6.15.0
Qt Version: 6.9.0
Kernel Version: 6.12.31-xanmod1 (64-bit)
Graphics Platform: Wayland
Processors: 12 × AMD Ryzen 5 7600X 6-Core Processor
Memory: 32 GiB of RAM (31,1 GiB usable)
Graphics Processor: AMD Radeon RX 7800 XT
Manufacturer: ASUS

ADDITIONAL INFORMATION
Example video demonstration of the issue: https://youtu.be/PDH7dsB6fwQ

Comment 1 Patrick Auernig 2025-06-23 12:01:30 UTC

Also noticed this issue with Factorio.
It doesn't just seem to run at a lower framerate, but actually slow down and stretch out in time.
This is most noticeable in the main menu when the demo scenarios are playing.

On the other hand games like Warframe seem to be completely unaffected.

Comment 2 Zamundaaa 2025-07-02 16:53:06 UTC

Wayland native applications using the FIFO protocol are limited to 30fps while they're not visible, which should be fine for games.
For X11 applications, Xwayland limits windows with VSync to 1Hz, there isn't really anything we can do about that. It would need to be changed in Xwayland.
In both cases we tell the apps about not being visible though, so this shouldn't cause any issues.

Are you actually seeing problems, or is this just about the overview preview being slow? If so, that was already fixed with https://invent.kde.org/plasma/kwin/-/commit/367eeb5f432271078f1fe98faf88df2dbc27cf93

Comment 3 Bug Janitor Service 2025-07-17 03:47:25 UTC

🐛🧹 ⚠️ This bug has been in NEEDSINFO status with no change for at least 15 days. Please provide the requested information, then set the bug status to REPORTED. If there is no change for at least 30 days, it will be automatically closed as RESOLVED WORKSFORME.

For more information about our bug triaging procedures, please read https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging.

Thank you for helping us make KDE software even better for everyone!

Comment 4 Patrick Auernig 2025-07-19 13:20:27 UTC

I upgraded to Plasma 6.4.3, which I assume includes the mentioned fix, and the problem seems to be completely gone now.

Comment 5 Patrick Auernig 2025-07-19 13:26:30 UTC

The only other problem I see now is that as soon as there isn't either a screen capture open, or the preview is shown the reduced frame rate can still affect an application that is hidden.
But that is both more of a bug in Godot (I've seen some issue reports that hint towards that), and a problem in how Wayland works.