It will feel faster because it will use the users time between actions to do the needed roundtrip calls.

Sure, if you preload all your sites' content, which I'm sure the users on slow mobile internet with limited volume and those on weak mobile devices will just love. But I don't see that happening in the linked article nor on the demo page.

Its 2020 not 2012. The small round trip calls on 4g are much more annoying than one call of a few a mb of data, in my opinion.