If you were having less than 512mb ram then you must always be wondering why firefox uses such a large amount of RAM. Well to limit firefox to it's RAM usage you can do the following trick:
Type about:config in the address bar
Now do the following:
Type about:config in the address bar
Now do the following:
- In the Filter text box, at the top of the page, typebrowser.cache.
- Double-click the "browser.cache.memory.capacity" entry.
- The default is 50000. If you don't have a lot of memory on your system, for example, between 512MB and 1GB, change the number to 15000 and click OK.