I figured out so far that AMP HTML greatly supports speeding up JavaScript, CSS and generally speaking rendering of the page.
However, yet another important speed topic in my experience are images.
How does AMP HTML tackle this issue such that images are perfectly compressed and resized for the current viewing device (tablet, mobile) and bandwidth (WLAN, 3G, Edge)
AMPs' image element amp-img supports the srcset (including support for the w modifier not natively available in Safari) and the sizes attribute in all browsers, so you can use modern responsive techniques to select the right image.
For now AMP itself does not do any image optimization itself. We might potentially start adding srcset attributes to image that don't have it on the proxy layer, but for now this is not happening.