CPU frequently rises to 100% and keeps slowing down

Plasma shell and kwin taking up most cpu.

Hi @avikmalfoy, and welcome!

In order to see what, if anything’s wrong, we need more information. To that end, please share more information, as per: [HowTo] Provide System Information, [HowTo] post screenshots and links and [HowTo] Increase your chances of solving your issue.