Pooya Karimian

Being a fast browser, Firefox will cache lots of stuff in memory and sometimes tends to be lazy releasing this memory even after you browse away from pages or even after closing some of the tabs. This will lead to a high memory usage (sometimes over 100MB) after hours of use. One work around for that is to restart Firefox. In that case using an extension like SessionSaver can help by restoring the old browsing session again, but still not that great.

A better solution that I found is to set the following preferences in Firefox. You can change them by typing about:config in the address bar:

config.trim_on_minimize = true
(MS Windows only. Determines how Windows handles memory for the browser when minimizing. Create it as a boolean value if it doesn't exist)

browser.sessionhistory.max_total_viewers = 0
(Number of history pages cached)

browser.cache.memory.capacity = 16384
(The maximum amount of memory to use for caching decoded images and chrome. Create this one as an integer, if it doesn't exist)

These parameters will decrease browser's responsiveness; instead it will have a smaller memory footprint. Also as a result of setting config.trim_on_minimize to true, whenever you minimize Firefox, Windows will aggressively take back as much memory as it can from browser. This will cause the memory usage to go down to 4-5MB. And the nice thing is that after you maximize the browser windows again the memory usage will be less than what it was before.

Also if you are the kind of user how don't want browser windows to be open and tend to close it as soon as you were done with your work and then open it again when needed, Firefox Preloader will improve Firefox startup time. It preloads a copy of Firefox without chrome in background, so clicking on Firefox icon will just open a new window fast.