This is the problem. You've seen it for SO long that "4:15-4:30" is now VERY quick. It's not. First step is getting to a place where that time is an average tournament round.
I played 18 holes in 2:35 the other day. We were a twosome, both shot in the low 70s… etc. But still.
4:15 is pretty fast for a foursome of college kids competing in a tournament playing the rules and an unfamiliar course and hitting cups. Seeing as how the standard pace of play is generally 4:00 to 4:30 for daily play, I don't think it's unreasonable to say 4:15 is pretty fast. I've heard of and seen college events that took six hours. 4:15 is very quick. Could it be faster still? Sure. But suggesting that college golfers in tournaments should play in 4:15 regularly will be regarded by many as so silly that it's easily dismissed.
My main point was that ball searches (i.e. which are partly controlled by course setup) can have a tremendous influence on pace of play. Golfers in a tournament are FAR less likely to waive a group through when they're looking for a ball or doing anything else that takes awhile (like waiting on a ruling or something).