Setting any advertisment host to 0.0.0.0 is a great idea, though I'm wary of doing anything like that, BitchX just caused a Major Fuckup on my mac, though OSX reinstalls quick.
If you haven't, set "ds.serving-sys.com" to 127.0.0.1. They seem to be the biggest offender in JavaScript firefox crashes for me (for those of you who get them).