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Comment by cramforce | Hacker News Reader

AMP doesn't implement scrolling in software. It is native GPU accelerated scrolling. iOS does have 2 modes and it might be that AMP hits the one some people don't like.

Edit: Filed https://github.com/ampproject/amphtml/issues/5125 to see if AMP can switch to other GPU scrolling mode.

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I'm with touche. Why in the world is AMP telling iOS to do scrolling different from other pages? What's the benefit? Why bother?

IIRC the iOS UIScrollView has a different scroll behaviour when it's inside a UIWebView. So they might have reset that difference.

Everything scroll related is in CSS. The long explanation is here https://medium.com/@dvoytenko/amp-ios-scrolling-and-position...

I'm well aware of how janky position: fixed on mobile. The solution is not to use position: fixed, not to try to "fix" it and make the experience bad.

Why does AMP do anything with scrolling at all?

Knowing where the viewport is relative to the document is pretty valuable; It means that AMP can defer loading potentially sluggish content until the viewport lands on a particular position.

Sounds like a premature optimization to me. The websites I tried did not have such requirements but the scrolling was just as janky nonetheless.

It's not premature optimization. It's optimization for ad revenue; they can charge more if they can prove an advertisement is visible on screen.

This is just CSS which exists for unrelated reasons.

For surveillance and user tracking.

Even if this would be correct (which it is not), it would only require to observe, not influence scrolling.

Maybe not in version 1. Think bigger, you'll get that promotion!

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