Try Java 1.6
FW won't use it if there's other java versions on your computer so you'd need to use the Add/Remove control panel to remove those versions. Then install Java 1.6 beta which has had good reports; http://java.sun.com/javase/6/download.jsp JRE "Offline" version which is a 14 MB download.

Go to FW's menu bar, Tools>Options & make some changes. Under Speed disable Ultrapeer capabilities. Under Downloads, reduce download speed to about 80% of your capability. Do the same under Uploads. Set both uplds & downlds to autoclear. You might also consider reducing shared files if you have multiple thousands of them. Tip: Purge the Downloads Queue!

After opening LW wait 10 to 15 mins or longer before using. Let it settle down 1st.

Also don't use the Resume button on all incomplete files. This can have side-fx such as affect FW's connection quality. May queue your files for much much longer. This will also stress FW & your comp. If you use Resume/Find sources then just apply it to a couple or so at one time.