Well, sometimes using cat is faster, as I discovered to my surprise recently:
https://news.ycombinator.com/item?id=14414610
But in that case one could probably say that Gnu awk is just not very good at input handling (as Mawk doesn't appear to benefit from an extra "cat").
but here's todays Useless Use of Cat Award http://porkmail.org/era/unix/award.html