Guild Wars 2

I know I should not even be able to play GW2 on my computer due to its low specs. But it runs fine for me. It just seems that after I close GW2, I have to reboot my computer or it runs real slow like the memory is tied up. Any suggestions on how to fix this, or could there be a memory leak.

Most probably the game uses all the free RAM and the system starts swapping the other applications. The solution is, as you mentioned, to restart the computer, or patiently focus every application to make the system switch them back to central memory. Or buy some more RAM.

^correct.
A memory leak would slow the game down after hitting the max address for a 32bit application (eg. FPS drops from 40 into the single digits and stays there until you restart GW2).