This guide will let you control the amount of RAM that the Firefox browser on your computer is using while you are on the web. This guide is particularly useful if your computer does not have a lot of RAM. Read below to find out how you can use the “about:config” page to maximize the performance of your computer without losing the ability to explore the internet.

The first thing you will have to do is open your Firefox browser and then enter the following URL into the address bar at the top of the browser:



This URL is a webpage that accesses he configuration values of your browser directly. Thus allowing you to edit completely the look, feel and functionality of your Firefox browser. Once you have typed in this address you will be greeted with a page warning you about the dangers of entering this page. The page will say “Here be dragons!”. Although, don’t be worried this is only to protect the Firefox settings of an inexperienced computer user so you will just click the “I’ll be careful, I promise!”. Once you have clicked this button you will be led to the configuration page which will contain a lot of values.


Now what you will need to do is enter in the “Filter” bar at the top of the about:config page the following text:



Once you enter this text into the Filter bar you will be left with a single value which will have a number value in Kb (Kilobytes) of your default RAM maximum for Firefox, which will usually be “51200”.


You can now change this value to anything you feel most fitting. I recommend the following:

Amount in Mb of System RAM         Recommended Kb For Firefox


     0 – 128 10000
128 – 512 15000
512 – 1024 20000
1024 – 2048 35000
2048 + 45000


As soon as you have edited the value to suit the total system RAM of your computer the you can resume using Firefox and the edited value will take effect next time you start Firefox. If you would like to see the effects immediately then open task manager, by right-clicking the start bar and then clicking “Task Manager” or hold “ctrl+shift+esc”.

It is that simple to decrease the impact on system performance that Firefox creates on your computer. Enjoy your new found Firefox configuration knowledge.