The mistake is to see that as a problem, and in need of some solution.People who want to be able to play their second shot when they reach their tee shot but can't because there is a slower group in front holding them up.
Telling the fast players to slow down or the slow players to speed up is not going to work.
It is simply a fact of life, dealing with humans, and the variability of golf (a 90 shooter with perfectly reasonably take 15 minutes longer to play 18 holes - ay exactly the same golf pace). People are not all going to take the same time to play a round. To expect so is unreasonable.
Such differences can be allowed for with longer tee intervals, thus building in some buffer time, or cencertina of the field. But that reduces the overall number than can be accomodated on the course. And so it is better just to have the faster players wait to play their shots.