Dear all,
I recently updated to fedora 40 (yeah, late to the party, I know) and since then, I am experiencing massive stuttering in KDE, whenever external monitors are connected to my laptop.
This is independend of the question, whether the external monitors are actually used, only connecting them triggers the behavior.
I have done some experimenting and came to the conclusion that the lag by the external monitors is worse, when they are connected through a usb-c docking station. The stutters are still there if the monitor is connected directly to the notebook via HDMI - they are however not as bad.
The stuttering occurs whenever overlay windows are appearing, e.g. when starting app-launcher (Alt-F2). The issue also may occur at times when resizing windows. Typically moving a window or putting a window in front/background does not trigger the stutter.
I have tried disabling the compositor (uncheck “load compositor at startup”) without any visible effect.
I enabled the performance overlay, which shows me, that every time a stutter occurs, the framerate takes a deep dive (“red bar”), if the external monitor is connected via HDMI and not via DP over USB, the dive is not that deep (“yellow bar”).
I have to use X11 and cannot switch to wayland, as I am forced to use webex which does not run on kde/wayland, so switching is not an option.
The notebook has only Intel integrated graphics, so I am not stuck with any nvidia driver issues.
Any thoughts?
Kind regards,
Jonathan