SUMMARY

When I log in with my user, the desktop grid animation is very fast and not so smooth. If I restart kwin with: $ kwin_x11 --replace ; the desktop grid animation is then slower and much smoother.


STEPS TO REPRODUCE

Note that I tried with a new user and couldn't reproduce, the desktop grid animation is identical even after restarting kwin_x11 process (too fast and not smooth). It only occurs with my actual user for some reasons.

1. Log in
2. Trigger the desktop grid effect: the animation is very fast (too fast) and not smooth
3. Open krunner and run `kwin_x11 --replace`
4. Trigger the desktop grid effect again: the animation is a bit slower and smoother


OBSERVED RESULT

The desktop grid animation is slower and smoother after restarting kwin (feels much better). The difference may not be obvious when watching the attached video but in real life it's very noticeable.


EXPECTED RESULT

I wish the desktop grid animation were always rendered like in the second part of the attached video (after restarting kwin_x11 process).


SOFTWARE/OS VERSIONS

Linux/KDE Plasma: Arch Linux & Gentoo (identical behavior on both distros)
KDE Plasma Version: 5.26.4
KDE Frameworks Version: 5.100.0-1
Qt Version: 5.15.7 / 6.4.1-1
X11
High refresh rate monitor (165 Hz)
NVIDIA GTX 970 with proprietary NVIDIA drivers (525.60.11)


ADDITIONAL INFORMATION

It's occurring since recent Plasma versions, I cannot remember the exact version but since last summer I'd say.

I'm not sure why restarting kwin_x11 process changes this, is this intended?

I know I can adjust the animation speed in System Settings but it doesn't fix the smoothness difference.

Thanks.