How To Reduce Memory Usage in Firefox with MemoryFox

memoryFoxHead   How To Reduce Memory Usage in Firefox with MemoryFoxDo you use Firefox? Most of our readers do and we all know that 10 open tabs can be highly problematic for our system memory. There have been times I have seen my Firefox get close to 1.5 gigs of memory. That is just unacceptable!

So what do you do? Do you stop using Firefox? Absolutely not! Will you use Internet Explorer? It is just as big of a resource hog and it causes system crashes as well (well it depends on what version you are using).

I have found a much needed extension to control and reduce the memory usage in Firefox called Memory Fox. You can grab the installer over here.

So to start, I took a look at my 4 open tabs in Firefox. They are using 256 Megs of memory. No big deal right. But a few hours from now that can balloon up to 4 times what it is. You can see my task manager open below with the Firefox process at the top hogging up my resources.

ff1   How To Reduce Memory Usage in Firefox with MemoryFox

And that is on a good day! What about my Vista machine at home that ONLY runs Firefox? Take a look at the 1.4 gigs of used memory below. Sheeesh! Apps should not be allowed to do that!!

ff0   How To Reduce Memory Usage in Firefox with MemoryFox

So head on over and install Memory Fox from the above link. You will need to check the checkbox next to the big green button that says Let me install this experimental add on. Once you click this checkbox you will be able to click on the big green button and download the extension.

ff2   How To Reduce Memory Usage in Firefox with MemoryFox

You will be prompted to restart your browser as usual. When your browser comes back up go to the tools menu and you will see a new entry towards the bottom for Memory Fox. You will have one option to activate Memory Fox or deactivate Memory Fox. I think those options are pretty self explanatory right?

So what did I do? I think I did what any other IT dude would do – I opened 25 tabs in FireFox with a whopping 1.2 gigabytes of memory in use right off the bat. Then I activated Memory Fox like so”¦

ff3   How To Reduce Memory Usage in Firefox with MemoryFox

and presto changeo ““ memory usage in Firefox dropped down to under 10 megs. It did jump back up to around 90 megs but the process from Memory Fox kicked in and dropped it back down to about 40 megs. And this is where we have been all day. I have not seen any other negative effects and it has indeed speeded up my web browsing.  Other tasks on my computer also have more resources due to FireFox being tamed.

ff4   How To Reduce Memory Usage in Firefox with MemoryFox

For those of you wondering what is behind this magic let us look to the author’s website:

Memory Fox focuses on two ( 2 ) types of memory usage and with flushing for memory recovery. When resource requirements ( Stack and Heap ) have been reached, according to the user’s preset option settings, the memory will be flushed and recovered from Fragmented Orphaned Ram memories.

Below are the two types supported for recovery.

I was unable to find my preset option but I know that it is 50 megs because that is when Memory Fox kicks in and reduces the memory utilization. All in all this is an amazing free utility and should be built into Firefox for sure!

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this is great.. thanks!


Works great! Over my expectations.

Although it wasn’t enough to check the “Let me install this experimental add-on”. I had to sign up and log in to finalize the installation…


When I used Firefox I changed a setting in my config that would trim the memory when I minimized the application. I’m not sure if it was just swapping it with the pagefile or not, but it seemed to really help me out on an old AMD Athlon XP.


“So what do you do? Do you stop using Firefox? Absolutely not! Will you use Internet Explorer? It is just as big of a resource hog and it causes system crashes as well (well it depends on what version you are using).”

…use Opera of course…


Memory Fox has been updated today to 1.03 however when trying to download it I just keep getting :- “Not a valid install package – 207″


Yup same here.


Anyone willing to share this through an alternate address, as the extension is no more available on firefox add ons website. Thanks in advance.


Fuc* Firefox, Go Opera.

Right now I have 6 tabs (+1 which is “Downloads”, so its 7 tabs). And yeah, it uses less ram that your 4 tab firefox + memoryfox.


hi!error package is not installable

Anne H

I can’t get it installed. It either gives me a Not a valid install package” or bad hash errors.

I tried from 2 diff windows machines


when I try to download “Memory Fox :: Add-ons” I keep getting : Not a valid install package – 207


Same issue at the above. Can’t offer any help… just posting so that I can get the auto-update when someone posts a solution.


Unable to install as I keep getting “Not a valid pakage install – 207″.


you need to have an account to download the MemoryFox latest version 1.3…as i did to successfully downloaded it & installed it on my firefox which i find did really owrks what ws said here…good luck on your next attempt to have it…


I dont want to nitpick, but I have got currently 10 tabs opened, and my FF (3.5.2) is using 165 MB memory, on XP. The maximum I have seen it go is around 300 MB, and that is when i have 25+ tabs opened.

And yeah one thing, just after starting firefox (only after starting it, not during usage) I run Cleanmem. Maybe that has something to do with less memory usage. But even without cleanmem, it does not go as high as as yours does.


I’ve even gotten to the point of having 200+ tabs open (I was mass-browsing photography portfolios) and it hit about 600Mb. And I dont even use any programs that lessen the memory usage. Right now I’m thinking a computer must be severely outdated if it begins to lag at only 6 tabs open.


No problem to download and install this now. My memory usage was instantly redused 10 times. Amazing :)

Downloaded this one:

Christopher Proudlove

Yeah … let me know when it’s fixed.


i was getting error 207 too
But strangely when i signed in to the addons.mozilla site the installtion worked the first time i tried ….

Christopher Proudlove


Bill Minton

I had issues getting it as well, but finally got it. Here’s a link to it –


The comments on the Add-On page repeatedly mention that the settings are a bit geeky. I agree even though I am considered to be a geek by my friends.

It now downloads and installs OK. Unfortunately I don’t think it is working as I am getting pop-up info boxes every few seconds saying “Memory Release Failed”.

I would suggest waiting for release 1.04


I had the periodic “Memory Release Failed” pop-up and solved it by setting atom.exe to trusted in Online armor.

Karl L. Gechlik

Wow! I do not know what happened between yesterday and today but I still see the version I used 1.01 available from this link

Try that and let us know how it works out.

Talk about bad timing!


I’ve just followed your link to version 1.01, downloaded it and with 25 tabs open it reduced my memory usage by 100Mb approx. Thank you, Karl.
Best wishes to all at MUO and enjoy the holidays.


Thanks Karl.

I did not need to remove “Confirmed” for the D/L to work and the simpler Options page implies V1.01.

NOTE for anyone else ‘downgrading’ – I did see mention of “Dissable befor Un-Install” on a page somewhere so I did that before clicking on the 1.01 link. It may not be required but might help.


Here is the updated version for firefox v3.5 â–¬>


The only way it appears to work is to remove the “?confirmed” from the end of the URL. It will make you sign into the site, presumably due to the experimental classification of the plugin. I was able to successfully install it by doing this.

Good luck!


I have a Vista running on HP machine & presently I am facing an issue with memory shooting up to 100% and fan start making noise. When I see the task manager I can see Firefox is eating all the memory. I will try this software (memory fox) today and see if it helps or not. anyways thanks for posting such a great info.


1.5 giga, i mean, really?? If I open 40 youtube videos in Opera I get around 900 mega. Yes, it takes forever to free the memory afterwards, so I usually kill the process. Still. I have never ever seen 1.5 giga of memory used.


FYI – You need to register and sign in with Mozilla or it won’t install properly i.e. gives an error msg about invalid package


Thank you all for sharing alternate links.


In task manager there are two processes firefox


Using it. Loving it.

Ron M Kolman

INCREDIBLE. Cut FF’s usage by half!
Thanks. Love it.


How is this better or different than SQL-lite Manager addon?

(PS: It would be great if Authors can compare to other existing, Non-Experimental addons.)

Thank you for the article.


I only have a gig of ram and my FF was using like 300k of resources everytime i was running it so my whole system ran really slow. Now that i have installed and enable memory fox the usage is only around 75k 80k average and everything runs like butter now!!!

Just great!!!


Just a question out of curiosity, what happens when your computer uses up “all” of your ram? I guess it crashes, but anything else?


this firefox add on really works great…to anyone getting error in downloading its latest version MemoryFox 1.3,all you need to do is to have an account in Mozilla official websites there you get it without a hazzle…Thanks to this site…


Everytime I use Firefox, my laptop frequently overheats or FF crashes. I use Google and Opera at the same time yet that doesn’t happen. Could the reason be FF memory usage?


MemoryFox is gone. Dead. No longer in existence.

Karl Gechlik

Strange it is still running on my machine. Anyone know where you can download it?

Bill Minton

Yeah, I just uploaded a copy to MediaFire –{1.09}.xpi

It isn’t going to stop running on your machine, there’s no “sync” setup between your addons & the website.