Bug 435138

Summary:	Assume that all full-screen applications want to block composition
Product:	[Plasma] kwin	Reporter:	Alberto Salvia Novella <es20490446e>
Component:	compositing	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED DUPLICATE
Severity:	wishlist	CC:	nate
Priority:	NOR
Version First Reported In:	git master
Target Milestone:	---
Platform:	unspecified
OS:	All
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description Alberto Salvia Novella 2021-03-30 06:51:19 UTC

Composition provides no value when there's a full-screen application running, for 95% of cases, and you can tell performance is smoother when turned off.

I don't know if the full-screen window is composited itself, but even if that wasn't the case having the rest of desktop elements being composited does nothing and decrease performance.

So it would be better disabling composition by default when there's a full screen application, as kwin-lowlatency does, while perhaps allowing composition for some full screen windows if they explicitly request so with a window rule.

Comment 1 Nate Graham 2021-03-31 17:29:33 UTC

Hmm, I'm not sure this is a good thing to assume. Turning off compositing can also result in more screen tearing (it does for me) and it also disables all shadows, which makes the task switcher look ugly when you use it to leave a Full screen window. And when leaving fullscreen mode or switching to another window there would be an ugly flash as compositing is re-enabled. Finally, compositing is always enabled on Wayland so doing would only take effect on X11.

If this is something you'd like to do for yourself, it can  be accomplished with KWin window rules.

*** This bug has been marked as a duplicate of bug 431736 ***