With all the video technology we have today that can show picture perfect replays from all angles, I wonder why the umpire can't just sit in the booth and make the calls from there (after seeing the replays). Have umpires on the field to spot the balls and all that but any questionable plays should go right to the booth where they can do a proper review and make the proper call.
It also shouldn't take that long. When I was watching the games, I usually knew on the first replay if it was a bad call or not.