Dust is why IT guys like me always have canned air handy. The main way dust kills performance is by clogging the air flow which raises temperatures inside the box. The computer is designed to automatically throttle performance as things get warmer.
Glad you got that resolved! ?
Only a little before my time to be out doing it, but that video definitely brings back memories of the 60's! (I had just gotten braces in 1969 and hated them!)