Well, considering this will be an in-game time run, the back track have to be there. The reason is, if you're going for in-game time, sacrifices have to be made for that, and if reentering the door saves one second, it could be arbitrary to avoid reentering the room. You wouldn't be legitimely going for in-game time, and wouldn't be going for realtime too. You have to choose a goal. I honestly think this run should be going for in-game time while optimizing realtime too, for example, if you're not going to loose in-game time, you can optimize door scrolling and stuffs like that. But one thing that should be avoided for saving just little time is pausing the game. I thought about one pause screen that could save some frames, but you would have to pause the game twice for enabling and disabling speedbooster, and the gains will probably be just a few frames, so i don't think it's worth pausing the game and breaking the action for that.
Edit: I think I understand now: It's my avatar, isn't it? It makes me look angry.
You mean when exiting into the main street? What would be the point?
