As a fresh KDE user I was disappointed in Klipper’s capabilities. I took the probably wrong advise to "remove /usr/share/plasma/plasmoids/org.kde.plasma.clipboard folder ". As a replacement I installed CopyQ which runs fine but slow i.e. it takes a second to paste something. Could this be related to the brute force used to get of Klipper? And is it possible to reinstall Klipper (and then silence it via “configure system tray”?
Don’t tinker on file level if you don’t know exactly what you are doing. This can break your system pretty quickly. Installing, removing packages using pamac or pacman is usually the right approach to handle programs/packages.
OK, so I re-installed. After a reboot clipboard seems to be fast. Klipper does not re-appear in the tray but can be run and then asks politely whether it should run. So, all good!