I can't test right now, but designating doors as 'Strong' may affect job assignment and/or other reachability checks (if you test this, you should save and reload after designating the door to make sure the reachability cache gets flushed).
Performance will likely be significantly affected when pawns have to path into/through avoid areas, though if it's not happening frequently it probably won't be noticeable. Better Pathfinding handles it much more efficiently than the Vanilla pathfinder.