I have 3 laptops (cheap/old and medium range) only using Intel iGPUs (two i3 and one dual core), the mouse movements became laggy, animations are rendered slowly and the whole experience is really worse and severe on Plasma 6.2. Disabling all desktop effects and setting animation speed to instant seems to improve responsiveness of the system and apps. Plasma 6.1 was truthfully perfect, smooth and fast, but 6.2 cannot be used at all.
I have a i7-6700K (4GHz), 32GB RAM and an Nvidia 4060, and I'm seeing the exact same problems with Plasma 6.2 (6.1 was fine for me too). The problem doesn't look to be related to any specific hardware. My system has openSUSE Slowroll installed, using the precompiled RPMs. kwin_wayland varies between 130% and 250% CPU; with 6.1 it was a fraction of this. I'll note that VLC can't display video with 6.2. Video playback in the browser (both FF & Chrome) is not at all smooth either.
I would like to add that even with all effects disabled, I found it hard to smoothly move cursor, even typed text is slow to appear, even the highlight color of border that appears around buttons, scrollbars, text fields..., when cursor hovers over them, takes longer to appear.
X11 seems to be really fast and smooth and doesn't suffer from any slowness with all defaults effects enabled, so the problem is only on Wayland.
The culprit is Night Light, it causes the slowness when it's enabled and only during its time of activation. I disabled it then rebooted and Wayland became usable again.
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kwin/-/merge_requests/6646
Git commit d9ce40c06f3bfb4da84d59be9c3b358281f9aa40 by Xaver Hugl. Committed on 16/10/2024 at 18:21. Pushed by zamundaaa into branch 'master'. backends/drm: don't skip colorops when matching the pipeline We combine all possible operations from the pipeline into one hardware color op, there's no reason to skip any - it just prevents matching a pipeline that could actually be represented in hardware just fine. M +0 -1 src/backends/drm/drm_colorop.cpp https://invent.kde.org/plasma/kwin/-/commit/d9ce40c06f3bfb4da84d59be9c3b358281f9aa40
Git commit d1eb9f0534cb454b173ce758d84956aae52b507c by Xaver Hugl. Committed on 16/10/2024 at 18:57. Pushed by zamundaaa into branch 'Plasma/6.2'. backends/drm: don't skip colorops when matching the pipeline We combine all possible operations from the pipeline into one hardware color op, there's no reason to skip any - it just prevents matching a pipeline that could actually be represented in hardware just fine. (cherry picked from commit d9ce40c06f3bfb4da84d59be9c3b358281f9aa40) Co-authored-by: Xaver Hugl <xaver.hugl@gmail.com> M +0 -1 src/backends/drm/drm_colorop.cpp https://invent.kde.org/plasma/kwin/-/commit/d1eb9f0534cb454b173ce758d84956aae52b507c
(In reply to medin from comment #4) > The culprit is Night Light, it causes the slowness when it's enabled and > only during its time of activation. > > I disabled it then rebooted and Wayland became usable again. Not in my case - wasn't enabled. I enabled it, and while the colours changed, the performance was the same. :-( Anyway, I see there's already a commit in. Looking forward to trying the new version.
I installed kwin 6.2.1.1 and rebooted, the fix really improved the slowness when Night Light is enabled, but it's not at the level like it was on Plasma 6.1, mouse and animations lagging is still noticeable. May be for people with powerful CPUs it's not noticeable but for my case it's still there. For now, speed, responsiveness and performance on X11 are better than Wayland.