Desktop notifications cause stutter on KDE Plasma 5.21.5

Whenever a notification appears (and dissappears), the entire desktop (both compositing and applications) stutters. It’s noticeable during daily use and irritating while gaming.

There also is some stutter when opening/closing windows, but I don’t know if this is related, and it isn’t that extreme.


I’m using KDE Plasma 5.21.5 with KWin 5.21.5, X Server 1.20.11 and GTX 660 with driver 460.73.01. The distribution is Debian Sid (KDE packages are from the experimental repo).

The same issue occured in past versions of both KDE and the Nvidia driver.

I can’t reproduce it on a Thinkpad x240 that has an Intel iGPU, but otherwise uses the same packages and their versions.

I have reported the problem to KDE, and they said it’s likely a problem with the driver, so I’m reporting it here.


  1. Open glxgears or similar, it can help to use mangohud to make the stutter visible graphically (it shows a performance graph).
  2. Open Konsole (any terminal really) and run:
     while true; do notify-send -t 2000 test; sleep 2; done
    in the shell. This will spam some notifications for you.
  3. Notice how whenever the notification appears, there is a visible stutter in glxgears and the performance graph from mangohud rises (if you launched glxgears with it).
  4. Move some windows around.
  5. Notice the lag whenever notifications appear and disappear.

nvidia-bug-report.log.gz (386.3 KB)

EDIT: New nvidia-bug-report.log with verbosity on X Server enabled.