Resizing XWayland & X11 windows is extremely slow

[Alexander Koskovich]

When resizing windows that are XWayland (Discord, Spotify, etc) the resize does not take effect until seconds after holding the resize. If you let go of the resize before it happens then window does not resize at all.

Ubuntu 25.04 Beta
NVIDIA RTX 5090 (570.133.07)

[Ubuntu Foundations Team Bug Bot (crichton)]

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[Alessandro Astone (aleasto)]

I can reproduce on non-NVIDIA.
Do you use fractional scaling by any chance?

> XWayland & X11 windows
What does that mean exactly? You can reproduce by resizing any window on an Xorg session?

[Alexander Koskovich (nexusprism)]

> Do you use fractional scaling by any chance?
Yes, 150%

> You can reproduce by resizing any window on an Xorg session?
Did some further testing, and I can't reproduce the issue with apps like Chrome or Ptyxis, but I can with Discord, Telegram, and Spotify. Only when they are inside an Xorg session or running under XWayland, if I force them to run as Wayland they are fine.

I turned off fractional scaling, and resizing is fine.

[Daniel van Vugt (vanvugt)]

Can you open a Terminal window and leave 'top' running before reproducing the bug? I'm wondering if any process (like mutter-x11-frames, gnome-shell or the app itself) is requiring too much CPU.

[Daniel van Vugt (vanvugt)]

See also https://gitlab.gnome.org/GNOME/mutter/-/issues/4061

[Alexander Koskovich (nexusprism)]

Is it possible to patch the GTK package to include https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/8459 while we wait for a new GTK release to come out?

[Alessandro Astone (aleasto)]

I can confirm that https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/8459 fixes the issue for me