Tips To Reduce Firefox Memory and Cache Usage

Reduce memory usage when minimizing

1. Start up Firefox
2. Type in about:config in the address bar and hit Enter
3. Right click and choose New > Boolean
4. Type config.trim_on_minimize in the pop-up box and hit Enter
5. Select True and hit Enter.
6. Restart Firefox

Reduce session history
browser.sessionhistory.max_entries determines the maximum number of pages in the browser’s session history, that is the maximum number of URLs you can traverse purely through the Back/Forward buttons. The Default value is 50.
We usually won’t surf more than 5 of the websites we previously surfed before, and there is really no need to store more than that in the session which can clog up memory as they grow.
1. Open Firefox
2. Type about:config in the Firefox address bar
3. Press CTRL-F and search for browser.sessionhistory.max_entries
4. Double click on the value 50 (or whatever value is there currently) and change it to something lower such as 5.
5. Restart Firefox.

Fixed cache capacity OR Disable Cache Totally
Every time new page is loaded, Firefox will cache the page so it doesn’t need to load again to be redisplayed. By default, this setting is set to -1 for browser.cache.memory.capacity and to a number you specified in Tools -> Options -> Advanced -> Network / Cache for browser.cache.disk.capacity

To fix your cache to a certain value:
*browser.cache.memory.enable and browser.cache.disk.enable needs to be True for this to work
1. Start up Firefox
2. Type about:config in the address bar and hit Enter
3. Search for browser.cache.memory.capacity and set a number in KB to use for the memory cache (ie. 1024KB = 1MB).
4. Search for browser.cache.disk.capacity and set a number in KB to use for the disk cache (ie. 1024KB = 1MB).

To Disable the cache Totally
Set both browser.cache.memory.capacity and browser.cache.disk.capacity to 0.
Alternatively, you can also set browser.cache.disk.enable and browser.cache.memory.enable to False.
Finally to Check Firefox Memory Usage
Type about:cache?device=memory in the address bar and hit Enter. Firefox will display your current number of entries, maximum storage size, storage in use and inactive storage.