what they do in the rendering pipeline or not regarding old data wouldn't keep the game from closing like you are saying it is.Sally, don't know if it can be of any help, but one thing i'm noticing very often upon exit, is that the game shows for few second a frame, from several minutes before i actually exited the game. For example i exit the game while landed at a station and inside my ship. I exit the game and i'm presented with this still frame (if i was in the concourse before, it's an image from there, or it might be me approaching the station, it depends from what i was doing before exiting the game).
It looks like old frames do not get flushed out of the rendering pipeline or memory. Sorry for the non technical explanation, not that tech savvy
That sounds more like the client is waiting for a response from the server before exiting and it's staying in a state that was never expected to be something that is visible to the end user for very long if at all.