With 512 megs of ram om my laptop and having installed some 100+ applications it doesn’t take long until I have 10+ tabs open on the Firefox. This came with a cost until now, ie huge amount of RAM being consumed (if the websites you go to have any sort of flash). This fixes the problem though:

1)Type about:config into the location bar and press enter
2)Right click any line to bring up a sub-menu
3)Choose “new”>”integer”
4)paste this into the dialogue that appears: browser.cache.memory.capacity
5)Next click Okay
6)Specify the amount in kb (about 70000 should do)
7)Restart Firefox and voila.