Prior to the most recent updates, GW2 tended to use about 2GB of memory. When clicking Exit to Desktop, it would close within seconds, and that was the end of it.
Since the latest patch(es), memory usage has increased, I have seen it at 4GB and continuing to climb (this is after a few hours of play). But I did not notice any corresponding increase in performance. Further, when exiting the game, the final frame remains on screen for an extended period of time - anywhere from 10s to over 30s, during which time the hard drive is very busy. Even after the window is closed, there remains a lengthy period of drive thrashing, which perfmon shows to be swap file operations (apparently Windows doing internal cleanup of memory that was not released by the game). Abnormal levels of drive thrashing can also be observed when alt-tabbing.
The oddity of this behavior combined with a lack of performance gains leads me to believe that there is a memory leak introduced in a recent build.