TBF I've seen a rare behavior in FF that makes some websites load slowly for no good reason (not an adblock thing). Anticompetitive either way but Google could be exploiting this bug.
I think you give them too much credit. From what I've seen, it's just a setTimeout call for 5 seconds if you're on Firefox, which is similar to what all those shady cookie popups from TrustArc do if you click "Reject all".
This happens all the time to me on Android. Sites, especially Google searches, sometimes take 30 seconds to 2 minutes to load. It's frustrating when I'm in a rush.