So last night I played for a while (probably 2-3 hours) without shutting down the game. The last thing I did was run around Gridania a little bit looking for vendors. I noticed my performance wasn't as good as before. I logged out and the first thing I checked was my memory. Yup, even after closing the game for several minutes, I was sitting at around 4.4GBs of memory being used with no explainable usage of that memory being listed in the processes other than the typical ~1GB windows 7 takes.
I'd search for this type of topic, but it looks like ZAM disabled searching for non-premium members again.