If you want to check the memory usage of the plugins, grab a copy of Eval and run /ee gcinfo(). (Although apparently gcinfo()'s been deprecated and you should be using collectgarbage("count").) Or write a script to print out the equivalent.
The highest number I've seen it get to was around 100 MBs, and quite frankly that was because my vitals display handles target effects - which has a memory leak (only if you get effects on a target) I haven't figured out how to avoid. Also, it happened after running several instance skirmishes in a row, so we're talking about a large number of mobs and players with a large number of DoTs and debuffs being targeted.