I don't know the exact reason, but the hanging seems to be caused by the (frankly ridiculously) large A* grid in some way. I removed some objects from the members list of the A* navigator that shouldn't be there ("PeopleSettings", Model Floor, Floor Plan) to stop it from auto resizing to this huge size. Then reduced its size to just about encompass the floor plan. That seems to have fixed the hanging.
Generally, after importing a layout you would change the location of the layout to be close to the origin of the model coordinate space instead of building the model in some far off corner. Mostly so you don't have to search for your model should you ever need to reset the view.
I also tried to fix some issues in your Patient flow. In "Radiation Therapy" the gowned waiting area was never released, leading to an eventual standstill. And in "Treatment Planning / Simulation" the structure of Gowning->SIM->Gowning while releasing the gowning during the sim would cause frequent deadlocks, as new patients would occupy the gowning, so the one in the sim can't acquire one and become stuck. The same could in theory happen in "Radiation Therapy" but the waiting area serves as a buffer in that flow, so a deadlock is much less likely to occur.
