Youtube has started to artificially slow down video load times if you use Firefox. Spoofing Chrome magically makes this problem go away.

Stop giving Google money. Use Invidious, Piped or FreeTube on Desktop, LibreTube or NewPipe on Android, Yattee with this guide on iPhone, iPad or Apple TV.

It's a little weird because its definitely slower on my desktop but on my laptop (with the same account, browser, and extensions) it's perfectly fine. I'm guessing that there's some AB testing going on.