Not saying it's true in the case of Youtube, but I've noticed recently that going back to lame old creaky page-refreshing HTML+(a little)CSS+a few lines of JS s

Not saying it's true in the case of Youtube, but I've noticed recently that going back to lame old creaky page-refreshing HTML+(a little)CSS+a few lines of JS sites with no AJAX that they feel unbelievably fast compared to most AJAX-heavy Angular/Backbone/React/Whatever sites. Ajax was better UX than full page refreshes when it was basically just replacing frames and iframes. It's become bad UX now that template rendering systems and a few hundred KB of code are involved. Actually, I just tried this with modern Gmail in one tab and the basic HTML version in another. It's way, way faster to switch folders/categories in the basic HTML version. It wasn't even close, despite modern Gmail "efficiently" loading just the data it needs and basic HTML refreshing the whole page.