Being a 6th year spectator (7th year at worlds total) I just wanted to add my thoughts. Unfortunately I do not have any suggestions at this time but I do think a few things are not being looked at deeply enough.
1 - After standing outside the milkhouse from 7:15 am until they let us in, we got seats facing the main doors. Security closed those doors before Large Senior even began. Approximately 8:50am people in our section were talking about the security standing in front of the doors detouring people - at this time I do not think they were actually keeping people out, I just think this was the beginning of the mess that was Worlds Day 3.
2 - I think no matter how the performance order & arenas go, there will always be certain divisions that will draw large crowds. (cheer drama? what is cheer drama?) Large Senior & Small Senior of course, this year was a big year for Large Coed with each of the "front runners" winning a major competiton during the season, and the Medium Coed division being a mix of some of the best Limited & Semi-Limited teams from the past few years. I honestly believe that no matter how the milkhouse performance order is set up, these divisions will consistantly fill it to capacity - it does every year. While all the divisions are equally important (please don't misinterpret this to being one is more important than the other), we all know the drama that goes on during the season and we want to see the final outcome of these drama-filled divisions- parents, participants (finalists and non-finalists), spectators, coaches, choreographers, etc.
Again, I wish I had a solution but at this time I have nothing.