It would be helpful if you said what hardware and OS you are using. It does make a difference.
Because Limewire is a JAVA app, it is a memory hog. If you're using a Mac and OS X, then the OS automatically allocates memory to different apps as needed. The more RAM you have, the more resources the OS has to work with. 128 megs RAM is a bare minimum IMHO.
If you're using a Mac and OS 9.x, then your memory allocation is set, even if a particular app is not using any RAM at any particular time does not mean unused memory is given back to the system to be used by other apps that may need it. You can increase memory in Virtual Memory, but are limited by the base RAM you have, as well as your hard drive space (the more the better for using virtual memory). Again, having lots of RAM here is even more critical.
I'm not sure how memory works in a windows machine, though I'm sure that the same is true--the more memory you have, the better off you are. Memory is still a cost effective buy, even tho prices have gone up of late. Many of my memory problems relating to memory vanished when I upgraded from 128 megs to 640 megs
Theala