How to deactivate all the desktop effects of KDE permanently?
System Settings > Hardware > Display and Monitor > Compositor
Remove ✔ mark from Enable compositor on startup
When this is done, make reboot.
EDIT: this answer is for KDE 4 - not 5
This can be done from:
System Settings > Workspace Appearance and Behaviour > Desktop Effects > General > Activation
A screenshot to show the menu:
And a lot of options in there to selectively block the effects so you don't miss out on all of the fun :)
In openSUSE Leap 42.2 , to turn off desktop effect. click settings > configure desktop> scroll down to display and monitor> compositor...un-click enable compositor on start up.