Whenever I leave Firefox open for more than a day or so, the memory usage always climbs up to illustrious heights. I have plenty memory (48GB) on my 64 bit machine, but for a 32 bit process this is useless anyway.
When usage becomes above 1GB Firefox becomes slower (it takes whiles before it shows typed characters, it may take seconds before it reacts to focus or tab change etc).
- Is it possible to have Firefox use less memory?
- Would that than limit usage or performance?
- Isn't it a problem for 32-bit processes to reach above the 2GB limit?
Using most recent version of FF 6, but this issue was around for all versions I can remember.

PS (edit): just tried once more to kill all but a few tabs, and this actually increased the memory usage up to 2.5GB. Clicking "minimize memory usage" on about:memory doesn't help even a bit.
plugin-container.exeis only for hosting NPAPI plugins, like Flash, Java, Silverlight, etc. Add-ons are hosted by thefirefox.exeprocess itself, and it sounds like either something is wrong with your profile or you have a buggy add-on. It's rare now, but I've seen cases where creating a new profile was needed to clear up crashes or other weird behavior. That said, most unbounded memory leaks in Firefox are the result of bugs in 3rd party code, either an add-on or a plugin. – afrazier Sep 27 '11 at 19:24