KDE provides a massive amount of desktop effects that are either visually very appealing and/or very practical. A common misconception among KDE users is that 'disabling desktop effects' makes the system faster in all cases.

The truth is that compositing will - generally speaking - render a desktop much faster if your driver implements it well, and therefore always disabling effects in KDE doesn't always give you a faster system.

Settings that will speed your machine up

• Go to Desktop Effects in System Settings.
• Under General, put Animation speed to Fast.
• Under Advanced, put Scale method to Crisp.
• Under All effects, review the effects and disable those you can live without.

See the KDE userbase article for more detailed information.