Switching workspaces lags: Can't update stage views actor <unnamed>[<MetaWindowActorX11>:0x56039dcafb10] is on because it needs an allocation.
On a Dell Latitude E7250 with an external HiDPI Dell monitor (3840x2160) connected, using Debian sid/unstable with GNOME Shell with X.Org (gnome-shell 43.1-2), after a while, switching workspaces started lagging. The journal contains:
Nov 21 10:19:00 e7250 gnome-shell[1538]: Can't update stage views actor <unnamed>[<MetaWindowActorX11>:0x56039dcafb10] is on because it needs an allocation.
Nov 21 10:19:00 e7250 gnome-shell[1538]: Can't update stage views actor <unnamed>[<MetaSurfaceActorX11>:0x56039abdb0b0] is on because it needs an allocation.
It’s not logged continuously though.
Nov 21 10:20:10 e7250 gnome-shell[1538]: Can't update stage views actor <unnamed>[<MetaWindowActorX11>:0x56039c8b6110] is on because it needs an allocation.
Nov 21 10:20:10 e7250 gnome-shell[1538]: Can't update stage views actor <unnamed>[<MetaSurfaceActorX11>:0x56039cda9690] is on because it needs an allocation.
Nov 21 10:22:18 e7250 gsd-power[1666]: gsd_power_backlight_percentage_to_abs: assertion 'value <= 100' failed