In the real world, airlines and handlers look to do everything as quickly as possible to ensure expeditious flow of traffic (and income!). However, I find GSX painfully slow. For example, only one service can take place at any one time. In the real world, refueling, catering and boarding often take place simultaneously. And when loading ULDs, the animation is very slow, with long pauses between each sequence. Even when loading with conveyors, the loader person seems to pause after loading three bags, then there is another pause before the cart moves, and another before he starts loading bags again. All of this can be painful to watch while all of the preflight procedures are done and you're just waiting for pushback to start.
