Nothing is throttling my CPU unless it’s somehow defaulted on in OpenSuse, Manjaro, Debian, or Linux Mint. Also these same distros, I installed other DEs on and had it work just fine. It’s a AMD Ryzen 9 3900x 4 ghz 12 cores.
This is specifically a KDE problem. So question, if you do windows key -> term/kon -> enter. As quickly as you can, does it accept the enter input and immediately launch your terminal?