Where is the lag coming from?

[Thallen]

Someone help me solve my little mystery. Now, I'm definately going to, first off, state that I do not have the best computer in the world. I have a whole 63MB of ram:


And a whoppingly amazing graphics...infestation:


Also, I'd like to make it clear that I have not the worst PC in the world either. I know a few players that manage to successfully play GK with even lesser the resources. Either way, I have this horrible, horrible lag when I play GK, and I'm wonder what it is coming from and how I can help it. If I stay in one inside level, I can play all day, no lag at all. But if I ever go from inside level to outside level, I move about 1 tile per 25 seconds, and no, I am not exaggerating. Could it be the transition of tilesets or something? How could I fix this? This is really limiting my play on GK, and I am virtually trapped inside the trading post.