[pferde]

The issue here is that nowadays "heavy applications of JS" are quite common on blogs, news websites and other "definitely not web applications"-type of websites.

With JS enabled, I sometimes see simple mousewheel scrolling slow down or become choppy, or spiking CPU usage for a second or two. Simple scrolling of content that is already rendered and is not moving. And often, the same site with JS disabled scrolls smoothly (or completely fails to load, it's a crapshoot, really).