When you log into your KDE desktop, there is a background service that starts - named kded and handles common infrastructural desktop activities. It may notify you of a usb stick you plugged into your USB port, or tell you that disk is running low. To help reduce some system cycles a thing you can do is to go through all the background services it loads, as your desktop computer might not have a touchpad or a wacom pad attached.

You can edit the list of desktop services by following these steps:

1. Go to System Settings, choose Startup and shutdown.
2. Open the Service manager panel.
3. Review every startup service carefully depending on your own use cases. If you disabled something that was important, enable it later on again.