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macrumors bot
Original poster
Apr 12, 2001

Mozilla on Tuesday officially announced Firefox 57, the new "Quantum" version of its flagship desktop web browser for Mac, Linux, and Windows. Aside from a redesigned interface and a slew of new UI features, Mozilla says Quantum offers speeds twice as fast as Firefox 52 and a new engine that uses 30 percent less memory than Google Chrome.


The performance advantages are said to be down to Firefox's "just right" multi-process architecture, which uses separate processes to run its user interface and tabbed web page content. These additional processes are able to run across multiple CPU cores, making it much less likely for open web pages to negatively impact each other or the performance of the web browser in general.

While both Firefox and Chrome now run using multiple processes, Mozilla claims to have done things differently to avoid using up precious working memory. Chrome creates a separate content process for each open tab, and each tab typically consumes hundreds of megabytes of RAM, which has earned the browser a reputation as a resource hog.


Where Quantum differs, claims Mozilla, is in its more conservative approach to using multiple processes. By default, Firefox now creates up to four separate processes for web page content, so the first four tabs each use those four processes, and additional tabs run using threads within those processes. This leads to multiple tabs within a process sharing the browser engine that already exists in memory, instead of each one creating their own.

In addition to the under-the-hood improvements, the redesigned "Photon" user interface offers a less cluttered, more minimalist environment for browsing the web and aims to look better on modern high DPI displays. It also adds several new features including a built-in tool to take screenshots, and a new library for putting things like browsing history, bookmarks, Pocket lists, and synced tabs in one convenient place.

Firefox 57 also includes support for WebVR, which enables websites to take full advantage of VR headsets like the HTC Vive, while Mozilla's Pocket service is now more integrated in the browser and displays trending articles on the new tab page. Last but not least, a new feature called Tracking Protection blocks extensive requests for online user tracking. It works by default in the Private browsing window and Mozilla reckons it reduces the average page loading time by around 44 percent.


With all the changes, Firefox has had to lose support for many existing extensions written in XUL. Firefox Quantum only supports WebExtensions, which have more limitations, similar to Chrome extensions. Existing users can check the status of their extensions by navigating to Menu -> Add-Ons. Compatible ones are shown under "Extensions", while deactivated browser extensions appear under "Legacy Extensions" alongside an option to find the closest equivalent replacement available.

If you're already a Firefox user, you should receive an automatic upgrade to Quantum after restarting the browser. For everyone else, Firefox Quantum is available for macOS as a free download directly from the Mozilla website.

Article Link: Mozilla Releases Firefox 57 'Quantum' Web Browser
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Reactions: samden


macrumors 68000
Jul 6, 2012
I like it, not throwing it over the side at this point. I definitely liked the old UI better, but it seems to work well with the new release (performance seems quite good).

The splash page is configurable (thank goodness) - turned pocket / advertising off immediately. Unfortunately your old top sites don't fill out the page like it used to (just the first row)...although based on their screenshot it looks like that can be built back up again.

Firefox (single thread) used to be very thrifty in memory usage compared to Chromium based browsers, now that it has multiple threads it eats up memory faster as well (seems less than Chrome, but not like it used to be).

How come? Mozilla syncs your stuff across devices. They released Quantum for iOS the other day as well.

I have to sync across PC's (work and home) and a work Android phone as well - is really pretty awesome.
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macrumors newbie
Nov 9, 2017
I do enjoy the browser speed, just might keep me around. One thing I'm not thrilled about is the Pocket integration, happily sticking with Bookmark OS


macrumors member
Sep 15, 2015
Does apple allow access to the keychain? I'd use Firefox a lot more if I didn't have to store login credentials in multiple places.
You could always use a service such as LastPass. Since I have Windows machines and a Mac I needed something that would work across ecosystems and I couldn't be happier with it!


Jun 22, 2007
I was a fan and user of Firefox since it was Firebird, and I love its bookmark+password syncing feature. But when webkit is becoming the de-facto engine, Firefox seems to be slow and fluttering around, to the point it got into the stupid version number race with Chrome.

Now, I just use Safari, and occasionally Chrome for sites with Flash. iCloud and keychain+1Password take care of the bookmark and password syncing. On the PC, I just use Edge, and Chrome as well for Flash content.
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macrumors 6502a
Jun 30, 2008
Was very excited about this, so I restarted to install the update. Prior to the update my tabs were using 550MB of RAM. After the update with the same exact tabs, now using 937MB of RAM. And I lost some add-on compatibility. Thanks, Firefox! :(


macrumors 6502a
Oct 4, 2003
I'm quite happy with Safari for now, but if that changes, Firefox will be my first alternative.

That said, what's up with tech companies co-opting scientific terms for branding purposes? Retina, Quantum, Photon, Neural Engine... I mean, I'm not gonna be protesting in the streets, but from a linguistic perspective this is certainly something to keep an eye on.


macrumors member
Nov 4, 2008
i was using the betas of quantum. impressed with the speed, but it was a HUGE battery hog. haven't tested the final though, hope they've fixed that.


macrumors 601
Nov 28, 2013
It doesn't use the keychain, "text replacements" don't work and pinch to zoom doesn't work.

On the plus side, in forums such as this one (and especially which is painful to use in Safari) I can back out of reading a thread and not have to wait a few seconds while the forum list shows, locks up, decides to redraw, and then action all the scrolling I'd done thinking it was ready. I really detest that "feature" of Safari so it's a balance of positives and negatives to me. It's also noticeably faster when bouncing around Facebook. I'm going to stick with FF for a while and see how it goes.

Edit: Someone above posted about ad blocking. I'm using uBlock Origin, and installing that on Quantum made me realise that the Safari version I have is out of date. So much for the auto-update feature of Extensions.

Edit2: I've not used Firefox for years. I forgot about "about:config". Enabled pinch to zoom. It's not smooth but it's working.
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macrumors regular
Jul 27, 2010
Larisa, Greece
This browser is incredibly fast but it has problems while watching youtube videos with resolution from 720p and above.
Trying to see what is wrong I've visited and I got this page:


I must state here that chrome is working fine with youtube and all these boxes are ticked in chrome.


macrumors 601
Nov 28, 2013
This browser is incredibly fast but it has problems while watching youtube videos with resolution from 720p and above.
Could you give a random example of a video not working for you? Full screeen or standard window? I just checked one of my video links that's 1080p and it works fine. I get the same "5 out of 6" browser supported features as you do.
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