How to Reduce Firefox Memory Usage using about:config

If you have noticed an increase of memory usage in recent Mozilla Firefox versions there are few tricks to Reduce Firefox Memory Usage. As you continue using Firefox overtime it gets slow. This is caused because add-ons you install, cache files and other Firefox memory leaks. Further, in latest Firefox releases is a noticeable increase of memory consumption. If you search Mozilla add-on directory, you will find some extensions for reduce Firefox memory usage. But installing another add-on is not quire appropriate in this case. So here we are going to discuss how to reduce Firefox memory U Sage without any add-on or without reinstalling Firefox.

Before we try following tricks it would be great if you can backup your current profile. So if anything goes south we can get back to the original state. To do so there are many software available for free. But I would recommend you to use MozBackup.

Reduce Session History in Firefox

Firefox remembers your page navigation order. It allows you to navigate among websites using Back and Forward buttons of the browser. These values are saved under browser session history.

It remembers up to 50 entries. Normally we do not hit 50 times on the back button right? So it is not an harm to reduce this number to something bellow 10.

1. Type about:config in the Firefox address bar. (and yes, promise to be careful)
2. Search for browser.sessionhistory.max_entries
3. Double click on the value 50 and change that to a value bellow 10.

Reduce Memory Cache in Firefox

Another way to Reduce Firefox Memory Usage is by reducing Firefox memory cache. Firefox uses PC’s physical RAM to cache web pages as you browse the web. If your PC does not have enough space available for a larger cache, you can either disable caching or assign a fixed value for cache.

1. Type about:config in the Firefox address bar.
2. Search for browser.cache.memory.enable
3. If you really want to disable caching abilities double click on true to set it false.

But I would recommend you to keep it as it is and assign a fixed limit to caching. So Firefox would not exceed that limit.

1. Type about:config in the Firefox address bar.
2. Right click on the windows and select New ► Integer.
3. Enter the Preference name as browser.cache.memory.capacity
4. Set maximum RAM that you allow Firefox to use in KB.

Idle Firefox When Minimized

Firefox keep using your RAM even when minimized. You can override this default setting. But keep remember if you do this it will take little extra time to restore the browser back.

1. Type about:config in the Firefox address bar.
2. Right click in the window and select New ► Boolean.
3. Enter  config.trim_on_minimize
4. Set the value as true

Bottom Line

In addition to all above tweaks for Reduce Firefox Memory Usage you can try following habits too. First of all, remember to use up to date version of Firefox. And use small number of add-ons. If you have not enabled hardware acceleration in options Enable hardware acceleration. This article from the Mozilla Knowledge base has some suggestions too.

Also you can read more about Firefox configuration options here.