It sounds like an extended version of Activity Monitor. Have you used it? It does also have some graphed display of memory usage. It's found in your Utilities folder.

Try this: 1. Tip: Purge the Downloads Queue!

2. Share no more than 2,000 files. Mac's Java seems to struggle with many shared files & incompletes.

3. Go to LW's preferences (keyboard shortcut: ⌘ ,) & select Speed & disable Ultrapeer capabilities. Also go to Uploads & Downloads in prefs & set to Autoclear.

4. Close all windows you don't need open at the time such as Connections window, Monitor window. Close off search tabs that have been sitting around for some time. Searches tend to go stale after a time anyway with people coming & going offline.

5. Don't use the Resume/Find Sources function on all your files. If used, just use it on 1-3 at a time.

6. After opening LW, let it settle for some minutes before using.

7. The problem with OSX's Java is not necessarily RAM usage as VM (virtual memory) & is often slow to rerelease it, & doesn't always release it at all. So if you notice RAM or VM suddenly increasing dramatically, close LW & that will release it. Then re-open LW to start affresh.

8. If still problems, reduce both upload & download capacity % slightly.

BTW 512 MB RAM is not a lot nowadays.