Why is that the longer FF is left on the more memory useage it takes. I've got enough memory that it is not causing problems and I have read about several work arounds for this trait. But I have never read a good explanation why it happens.

I usually keep 3 to 4 tabs open. When I first open FF it uses ~100K, then a couple days later it's up to ~200K, then a few days later it's up to 300K with generally the same tabs open.

Why the growth?FF saves the pages that are in a tabs history in RAM. (for example, when you press back, it loads the page from memory)

so the more browsing yo do /tabs you have open, the more ram it consumes.

For example, I have 22 tabs open, of which about 10 have fairly DEEP history queues- FF is consuming 596,116 KB.

However- even closing the tabs doesn't help- because it saves the tabs you've closed, too. (probably just hides the buttons). This is why it constantly rises. there is a "browser.sessionstore.max_tabs_undo" that can be changed with about:config that might help to reduce RAM usage from getting too high from a large number of tabs.

OK, thanks. Makes SENSE now.You can also disable session manager which is remembering where you are at and is designed to take you back there if FIREFOX or the machine is turned off unexpectedly...
Nice feature but it also gobbles up resources...hi patio, i'm looking in my Firefox options now but can't figure out the session manager thingy, can you please teach me how to disable it?

or is this exactly what you mean? Options window - Privacy panelI apologise...
I forgot it is an extension/addon for Firefox...
If you don't see it on that page then it's not installed...I see. Thanks!You can also disable session manager which is remembering where you are at and is designed to take you back there if Firefox or the machine is turned off unexpectedly...
Nice feature but it also gobbles up resources...
http://windowsxp.mvps.org/registry.htm too bad that link is completely IRRELEVANT...Number of add-ons is another culprit. The more you have, the bigger RAM usage.
Some add-ons are known for memory leaks. List: http://kb.mozillazine.org/Problematic_extensions
Experimental add-ons acquired through GreaseMonkey are the worst.