Bug 431385

SUMMARY
using krunner after update to plasma 5.20.5 leads to the whole plasmashell hanging, or terribly lagging. I have to killall krunner to get back to normal.

STEPS TO REPRODUCE
1. start plasma desktop
2. use krunner


OBSERVED RESULT
Desktop hangs, one CPU core at 100%


SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: Fedora 33 5.9.16-200.fc33.x86_64
(available in About System)
KDE Plasma Version: 5.20.5
KDE Frameworks Version: 5.78.0
Qt Version: 5.15.12

ADDITIONAL INFORMATION
The following lines are logged endlessly until I kill krunner:
gen 10 11:11:28 localhost.localdomain plasmashell[1280]: kf.service.services: The desktop entry file "/usr/share/applications/qemu.desktop" has>
gen 10 11:11:28 localhost.localdomain plasmashell[1280]: kf.service.sycoca: Invalid Service :  "/usr/share/applications/qemu.desktop"
gen 10 11:11:28 localhost.localdomain plasmashell[1280]: kf.service.services: The desktop entry file "/usr/share/applications/kde/kresources.de>
gen 10 11:11:28 localhost.localdomain krunner[2699]: kf.service.services: The desktop entry file "/usr/share/applications/qemu.desktop" has Typ>
gen 10 11:11:28 localhost.localdomain krunner[2699]: kf.service.sycoca: Invalid Service :  "/usr/share/applications/qemu.desktop"
gen 10 11:11:28 localhost.localdomain krunner[2699]: kf.service.services: The desktop entry file "/usr/share/applications/kde/kresources.deskto>

I don't have any new desktop shortcuts to blame on.
Note that the plasmashell entries above do appear only when there's krunner madding in the bg. This (to me) indicates some sort of relationship which you might understand.