It's an iPhone 8. Safari with content blockers.

Then I mostly don’t believe you. Benchmarks please, I doubt you are unable to load a JavaScript heavy site.

I never said I was unable to load it, I said that the AMP site is noticeably faster. The problem is my currently slow network, not the phone. My phone processor gets the same single-core benchmark speeds as my desktop processor, so that's not the bottleneck.