Hm. As far as perceived performance, I recently wrote a proof-of-concept library using a timer and calculating viewport intersection of an element. It feels les

Hm. As far as perceived performance, I recently wrote a proof-of-concept library using a timer and calculating viewport intersection of an element. It feels less annoying than a registered scroll event, although I did not do any instrumented performance comparisons. (The point of the library was progressive enhancement, not performance.)