If you count the 24 hours I allow for the epoxy to dry, then turning a tenon is quicker. If you don't count the 24 hours I allow for the epoxy to dry, then delrin is quicker.
With the delrin, cut it (I buy it in 4 ft lengths), chuck it in the lathe, drill it, cut a groove in it and the stem, trim the end to the correct angle, mix the epoxy, then insert into the stem, wipe off the epoxy that runs out, then after it dries, drill out the dried epoxy, chuck the stem into the lathe and trim the tenon to length. Sounds like a lot, but it goes pretty quickly.
I think Tyler said in one of his posts that it takes him about 30 min less to do the delrin than to turn a stem. Although i have never measured the time, I think Tyler's estimate would be on the low side for me, as I work slow, and since I do not have much experience turning tenons, I go really slow with this operation (although with experience the time will decrease).
Overall, I think some makers prefer turning tenons and some prefer delrin. I wanted to be able to do both, but I will primarily use delrin.