New Firefox Quantum Twice as Fast, 30% Less Memory

John Lister's picture

Mozilla has launched a new version of the Firefox browser aimed at winning over Google Chrome users. It says the new version is twice as fast as earlier versions of Firefox that were available this year.

The key is the "web rendering engine," which is the part of the browser that interprets the code on a website page and visually combines it on the user's computer. Mozilla has replaced its old engine with a new one dubbed Firefox Quantum. It's also put together videos showing that Firefox is now quicker than Chrome to fully load most (but not all) of the more popular websites.

Independent reports suggest these claims are viable. They also note that the new browser feels faster in several other aspects such as typing website addresses. (Source:

Browser Does Two Things at Once

Part of the difference is that unlike previous editions, Firefox is set up to work better on computers that have multi-core processors. These systems are able to work on multiple tasks simultaneously because more CPU cores means more available 'hands' to get work done. The new browser splits out the various tasks involved in displaying and using a web page and assigns these tasks to different cores.

Mozilla also took aim at Chrome by saying Firefox now uses 30 percent less memory. It's unclear if that will be the experience of all users as it may vary widely depending on their computer and web use. However, it's certainly fair to say that heavy memory use and resulting freezes and slowdowns is the most common criticism of Chrome. (Source:

New Firefox Interface Decluttered

Other changes include a cleaning up of the browser so that there's less clutter on the screen beyond the actual webpage. This includes using the same space for both typing website addresses and carrying out searches - something that's already common on most rival browsers.

Firefox also now has a single "Library" button that gives access to tools such as bookmarks, a downloaded files and browser history, rather than have multiple menu options permanently displayed on screen.

Firefox 57 (Quantum) Kills Many "Legacy" Addons

The new Firefox Quantum also includes the WebExtensions API (application programming interface), which manages Firefox addons. The biggest change means that older extensions which have not migrated to the WebExtensions API will no longer be compatible going forward. In other words: many addons will simply be disabled until (and if) the author decides to migrate to the new format.

What's Your Opinion?

Do you use Firefox as your browser? If not, would these changes make you more likely to try it out? What are the most important features in a browser for you?

Rate this article: 
Average: 5 (7 votes)


Dennis Faas's picture

Just this past week, Firefox consumed 6.4GB of RAM (memory) on my system and ran incredibly slow - and that's with only a few tabs open.

Firefox's memory consumption has been a major issue for the last 1.5 years or so, with the average memory consumption hovering around 2.5GB "daily usage". That is more than half the memory of most PCs that have 4GB of system memory!

When Firefox first loads, it eats around 300MB and grows exponentially with each page load. I have disabled my extensions, created a new Firefox profile, formatted the PC - and it still ate about the same memory. This is with Firefox 64-bit - that may be the reason.

I am interested to try the new Firefox Quantum but am not looking forward to losing my addons, including the Tab Groups which allows me to categorize and store my tabs - which I have grown so incredibly fond of over the past few years.

Dennis Faas's picture

I rebooted my machine and Firefox 57 automatically applied. I did find a "Tab Group" addon compatible with WebExtensions, available here:

Update: found another one - this one seems a little more intuitive when it comes to moving tabs around.

LouisianaJoe's picture

Before you just click bookmarks, then folder then bookmark.

Now you click library, bookmarks, all bookmarks. It then opens up a new window where you click folder then double click book mark and then you have to close the bookmark window to make it go away.

What were they thinking. I am now more likely to use a different browser.

supernovatj_10151's picture

You don't have to go to Library in order to get to your bookmarks. Just (I am assuming you don't have this activated) right click on topmost bar and check "menu Bar" and when it appears bookmarks will be shown along with File- Edit...

LouisianaJoe's picture

Thanks for the info. That works.

NickyK's picture

I installed it yesterday on my main (desktop Windows 10 Fall Edition) PC and found it incredibly slow. Even after “cleaning” the PC and rebooting, it was painful to use. Furthermore, add-ons that I like and/or use regularly had gone (with the developers, in some cases, saying they would not be providing new compatible versions). Worse still, for these few add-ons I use, there were no suitable replacements.

Consequently, I uninstalled "new" Firefox and then installed the previous version (with all add-ons back, passwords and bookmarks preserved).

I have switched off automatic FF updates for the time being. I will install the new FF on my lap-top and see how things go. I hope and expect the time will come when my add-on desires will be satisfied and I can upgrade happily.

Dennis Faas's picture

I've been using Firefox 57 for a few hours and it is WAY faster than previous editions. I am using the Ryzen 1700 @ 3.8GHz overclocked - 8 core, 16 thread CPU. Also, memory utilization is WAY better than previous, currently using 1.2 GB of RAM.

jpbleau_7629's picture

As a web developper, I tried the new developper edition and it is really good. Much faster and offering a lot of useful tools for the web developpers.

supernovatj_10151's picture

Hello Dennis. I'm using FFQ also and, I too, find it somewhat faster. However when I looked in the Task manager to see how much memory it was using I noticed far better than yours (850 mb) I know millage may vary according to user. But I noticed that it was running multiple instances of FF. When first open, it opens 4 instances by default. As more tabs get invoked, it adds more instances. If I close all the tabs except one, it still shows 4 tasks running. Is this normal?
Thanks, I love your site.

Dennis Faas's picture

Seeing multiple Firefox instances is normal - Google Chrome has done the same for quite a while. I haven't used Firefox 32 bit in a while but I believe they started using multiple instances not too long ago, though this was not present in 64-bit editions until now. The new Firefox Quantum also takes advantage of multiple cores, as this article mentions, which may have something to do with the multiple instances.

dave_9226's picture

As a "security feature", Firefox V57 prohibits user scripts. I have a job critical Greasemonkey script that saves me and my staff hours of typing every day, and it won't work under FF V57. I spent all day reverting all the office machines to version 56.0.2 and turning off the automatic updates.

I didn't see any significant speed improvements on any of the pages I visited, and no amount of speed improvement would counterbalance the disadvantage caused by losing my job-critical user scripts.

I find the new user interface cosmetically unattractive, and it forces the tab bar to be on top like IE, where I'm not used to it. The previous "Classic Theme Restorer" add-in no longer works, and according to its author, cannot be adapted to subsequent FF versions.

I found a fork of Firefox called "Waterfox", which purports to offer the advantages of the latest version while maintaining backward scripting compatibility. However, it would not recognize my current FF profile, perhaps because I keep it on a non-standard location. I'll have to work on that in my "spare time".

rohnski's picture

Since I installed FF57 I have had 3 warnings from Win10 about low RAM, forcing me to close apps. Before that I had never seen that message.

Speedwise it is a draw. After I added an adblocker it is adequately fast. But so were earlier versions.

But, the new version killed NoScript. The only replacement I could find, "uMatrix", is much slower. It provides more control, but therefore takes longer to get a page to work.

The new version also killed the main reason I stayed with FF this long. An addon called PlainOldFavorites that enabled FF to use IE favorites instead of the "new & improved" databases. I NEED to be able to do file name searches for favorites and files on my system. Putting favorites into an application specific DB makes sharing inconvenient. And No, I don't want to share my links with someone on the internet.

PS: your comment process is confusing

NickyK's picture

This is from NoScript's website:

"2017-11-14: We're working hard to make NoScript for Quantum available to you as soon as possible, definitely by the end of this week."

sytruck_8413's picture

Just installed it and brought over all my tabs. 25. Haven't checked addons, I don't use many, but I can tell you that it is probably twice as fast what I was using. Cyberfox 64. Switching between tabs is instant. Surfing my common sites seems much faster. Page loading is much faster even once "inside" a site which would slow down Cyberfox seems to have little effect here. I'll keep at it and edit this comment if necessary.

Memory use with the same number of tabs is 117 vis 340 MB Cool!!

ghostwriter's picture

I don't much care for FF. The way FF handles bookmarks and everything else in my opinion is terrible. Backing up bookmarks is even worse. Chrome and Opera handle bookmarks a lot better. For instance, If you change your bookmarks in Chrome you can back them up this way. Open up a file manager program. Go to C:\Users\your name\app data\local\Google\Chrome\User Data\Default\ Scroll down to the bookmarks file and copy the file to a different drive and label it Google bookmarks. If for some reason you install a previous image all you have to do is copy the bookmark file you saved back to the original location. You can copy the same file to where Opera stores the bookmark file. Much easier.