Hi,
So, today morning I updated whole f41 system and restarted machine as usual. For some reason, everything is veeeery slow in KDE.
Plasma program menu takes 3-4 seconds time to open. Browsers are extreamly slow. Everything is totally unusable.
I start going through what’s going in system: top/btop show that mem is plenty left, CPU’s idling.
I check network interfaces (I use NFS homes), everything normal, interface speeds are normal. iftop doesn’t show unusual amount of traffic.
I install lxqt* and log in to that desktop. Everything is snappy and extreamly quick. So it cannot be display drivers. I’ve old machine but it’s enough for what I do.
I switch off rest of the desktop effects from settings, no help.
I come back to KDE and start going through what is running in the system: systemctl --user | grep running has a lot of stuff that I don’t need. I stop most of them, there are only left window manager, plasma, dbus and some other. Still the same slow symptoms. Unfortunately
kcmshell6 kcm_systemd
is broken.
I’m out of what to try next. I ask around, nobody has good ideas.
I keep looking around, xrandr etc. Just for the giggles I go back to KDE display settings, nothing unusual. I have two DELL displays extending desktop to another. I keep the reso, but click the primary to the left display, it was on right previously. The the plasma panel and desktop directory icons swap to the left screen and - tadaa! Everything starts working quickly as usual.
I swap the primary display back, the sluggishness comes back. I fix it again and it’s quick again.
I could never believe that this could cause it.
% kinfo
Operating System: Fedora Linux 42
KDE Plasma Version: 6.3.5
KDE Frameworks Version: 6.14.0
Qt Version: 6.9.0
Kernel Version: 6.14.6-300.fc42.x86_64 (64-bit)
Graphics Platform: X11
Processors: 8 × Intel® Core™ i7-2600 CPU @ 3.40GHz
Memory: 11.6 GiB of RAM
Graphics Processor 1: AMD CAICOS
Graphics Processor 2: AMD CAICOS
I hop this helps someone else having KDE slow problems, it’s quite common when you google it and I’ve had it few times as well. And these are extreamly difficult to figure out, there are so many probable causes where to look from and desktop daemons, buses etc interfaces are complex today.
Tuju