Simple suggestion.
Of course, I have no idea what difficulties this would entail.
It could be really beneficial to separate FWSim from the World Editor. This would save a lot of time on loading. If I want to directly edit a 3D world, I have to wait for the world to open in FWSim first, then again in the World Editor. Once finished… another loading in FWSim. I hope I am clear enough.
Another option: FWSim opening on a new project instead of the last project.