Google AMP lowered our page speed, and there's no choice but to use it
AMP is just a set of conventions and limitations that, when followed, make for a fast site. Anyone can make a fast site if they follow similar rules. Most sites don't do that because either the developers want to use something that's "nicer" to code but a lot bigger, or because the marketing department insists on loading 12 different tracking and analytics progams--when they probably only use one or two.