Can I make Firefox take up less memory on a slow comp?

Well, Firefox sometimes freaks out on my computers too. Like he said above, you can use the preloader to speed things up or check your add-ons. If you have to many, that will slow down things too. Also, check your memory usages! Hope this helps!

Firefox using 144,000k sounds about right. Users usually report that firefox uses between 100 and 150Mb of ram being used by firefox. Right now firefox is using about 256Mb on my machine. Some extensions can cause memory leaks on firefox. They are: IE Tab, Session Saver, ForecastFox, Filterset.G Update used with FlashGot all cause memory leaks on firefox. The extensions: Tabbrowser and FoxyTunes slow down firefox. You can also tweak the internal settings to configure how much memory firefox uses. The articles here: http://kb.mozillazine.org/Reduceing_usage_(firefox) can help you reduce memory usage. Also you can use seamonkey which is based off of firefox and most of the extensions do work on it but it is smaller and lighter than firefox.

I think this is the consequences of firefox having to many features and being a secure one. I could remember the old version is a lot faster. Firefox 3 beta load faster but that's because it has little addon. I just hope the final release of firefox 3 would do much good. As for you I would suggest removing the theme, use the basic or default. Graphics are really memory hungry. Try to limit the addon, disable some if you have to just turn them on if you need them.