Josh the web developer has probably experienced slow down animating shadows, whereas you're just guessing. Maybe give the author the benefit of the doubt, or m

Josh the web developer has probably experienced slow down animating shadows, whereas you're just guessing. Maybe give the author the benefit of the doubt, or make an example disproving his theory. There are plenty of css performance gotcha's you wouldnt expect. Changing gradient backgrounds on body (or a big div, I forget) everyframe is fine, but changing it on html (for ios safari's outside-the-body app colours) is horrendously slow and actually causes visible tearing when animating. We could just assume theyre "the same", but with experience, you find they are not.