System Settings/Desktop Effects
The Desktop Effects module allows you to control what graphical effects you want to use for your workspace.
Desktop effects gives your workspace the look and feel of a truly modern system, but it comes at a price. Desktop effects requires modern graphics capabilities. If you are using an older machine, desktop effects may not be possible, or may make your system sluggish and unresponsive. In that case you can still use your Plasma workspace; just make sure to deactivate the desktop effects.