Bug 506061

Summary:	Using 60Hz refresh rate on screen capable of 165Hz produces more input lag on Wayland compared to X11
Product:	[Plasma] kwin	Reporter:	statauskersa33
Component:	input	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	REPORTED ---
Severity:	normal	CC:	cornerboost, duha.bugs, nate
Priority:	NOR	Keywords:	efficiency-and-performance, wayland-only
Version First Reported In:	6.4.0
Target Milestone:	---
Platform:	NixOS
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description statauskersa33 2025-06-23 16:34:13 UTC

SUMMARY
I want to disable vsync on desktop, which on Wayland probably means allow always tearing option in the settings

STEPS TO REPRODUCE
1. Use KDE Plasma 6.4 with Wayland 
2. 
3. 

OBSERVED RESULT
Input delay on mouse feels significantly higher than when comparing a desktop without vsync (X11).

EXPECTED RESULT
Settings switch to allow always tearing display in settings.

SOFTWARE/OS VERSIONS
KDE Plasma Version: 6.4

ADDITIONAL INFORMATION
Using the display at 165hz is consuming more electricity than when using with 60hz. But on Wayland KDE Plasma, VSYNC is always forced on. This was the reason stopping me from using Wayland at all. I want to be able to use my computer at 60hz refresh rate not not feel the input delay caused by perfect frames. Please let me know if there is an alternative method to enable this while I wait for the possibility of having this functionality.

Thank you for building the best desktop environment and for your time.

Comment 1 Nate Graham 2025-06-24 18:41:57 UTC

I think it would make sense to step back and describe the specific issue you're experiencing here, rather than requesting a bunch of features that may or may not actually fix the issue.

The issue is that you experience more input lag on Wayland when using a 60Hz refresh rate, compared to when you do this on X11, right?

Comment 2 statauskersa33 2025-06-26 10:09:38 UTC

(In reply to Nate Graham from comment #1)
> I think it would make sense to step back and describe the specific issue
> you're experiencing here, rather than requesting a bunch of features that
> may or may not actually fix the issue.
> 
> The issue is that you experience more input lag on Wayland when using a 60Hz
> refresh rate, compared to when you do this on X11, right?

Yes.

Comment 3 Nate Graham 2025-06-26 15:53:05 UTC

Ok, let's make the bug report about that.

Comment 4 Gemskip 2025-09-30 06:26:19 UTC

(In reply to Nate Graham from comment #1)
> I think it would make sense to step back and describe the specific issue
> you're experiencing here, rather than requesting a bunch of features that
> may or may not actually fix the issue.
> 
> The issue is that you experience more input lag on Wayland when using a 60Hz
> refresh rate, compared to when you do this on X11, right?

This isn't a bug, this is a feature difference between X11 and Wayland. The monitor refresh cycle on 60hz is long enough (~16ms) that the act of holding back a frame for one or more refresh cycles to make sure they are perfect results in easily humanly discernible lag and is the source of most of the input latency on a standard office PC or laptop. I don't know how much you are buffering, but you are not going to be able to optimize enough to remove the perceptible difference while keeping your frames clean. It is a sacrifice that all modern desktop compositors knowingly make. High-refresh rate monitors just brute-force the problem by having more refreshes.