We already know that in the third version of Firefox there will be much less memory, but what do the owners of the two. And you can do the following:
Disable unnecessary extensions
Enable memory release while minimizing
Configure cache correctly
Extensions
The first thing to do is disable unnecessary extensions. The optimal number of extensions is from 5 to 10, although I personally use more. In addition, there are extensions that lead to memory leaks: Adblock, Fasterfox, IE Tab, Session Saver, Adblock ( Adblock Plus should be used instead) - the source . ')
Setting cache and freeing memory
Open the about: config page and change or create (right click with the mouse) the following values:
config.trim_on_minimize set the value of the type boolean set to true (works only for Windows)
browser.cache.memory.capacity set integer value to 16384
browser.sessionhistory.max_total_viewers type integer set to 0
Links (in English)
There is information on fine tuning memory in Firefox