I can't confirm if this a problem for everyone using quantum but I'm unable to vote on voting based questions here!

QUick update to my previous response, since I only discovered it today (disclaimer, I worked on fra stuff for many weeks and haven't played with API dev for a little while)

Quantum has a built-in json viewer which is really nice, no extension to add (and it looks better than the ones I used in Chrome and Canary, although I haven't played with it yet to see how it behaves with large JSON documents). HAving this directly built-in, with filtering and a nice treeview is definitely a welcome addition imho.

I've tested it for half a day and it triggered me so much I had to stopped... I really wanted to like it. Get away a bit from Google, promote the open-source and all. Maybe next time.

My local project takes 900ms (with all dev profiling included on Chrome) but loads in not less than 4.5s on Firefox 57. Additionally, I get 137% of CPU usage with 3 tabs. Just unusable for working. 😔

I hope it's just a bug that will be fixed. I'll try again in a few weeks. 🙌

It's super fast!

So I use it for my daily browser even in my iPhone.

But for the development, I use Chrome which is the first recommended browser for our clients. And I like to use alternative dev browser.

I love Quantum! It has an amazing design, is super fast and has cool features. I think it will be my new standard browser. :)

I'm liking it so far. Actually, this is the first time I'm properly using it for something other than quickly opening it to see how it looks/feels. I'll stick with it for a few days but, like with other browsers, I fear the issue might come from me not being used to the dev tools like I am in Chrome. If Safari had better dev tools I would've been using that over Chrome for a while.

I'm finding it a mixed bag. The JavaScript performance improvements were SHOCKING as prior to the new engine Spidermonkey was anywhere from half to a fifth the speed of V8. Now with quantum it's on par if not faster. With the massive amount of scripttard bloat on websites, this is a welcome improvement as to be frank the old engine was aging like milk left out in the sun on a hot July day... it had turned green and there was a tree growing out of it.

The new "cleaner" interface is a bit... I dunno... That it put flexible spaces before/after the address bar didn't exactly wow me, but those were easily enough removed so that the FULL free space of the screen can show the URI. I do find I prefer the 'light' theme over the default, but that's just cosmetics.

"top sites" remains the same useless crap it has always been, naturally this gets replaced with a more Opera-like speed dial, sadly none of them are as capable as what Vivaldi does out of the box. Wow, am I an old-school Opera fan from before they told loyal fans to **** off or what?!?

I do not like how the old web developer toolbar add-on is no longer allowed to show as a toolbar, but is a tabbed based drop-down. This seems to be the mold now for add-ons and whilst I would like it as an OPTION, there ARE toolbars I use all the time since I would be a very hard sell to use FF as my daily driver. I'd be far more likely to embrace it if I could do simple things like portrait mode tabs out-of-box without goofy crap like "tree's" that the add-ons do. Again, Vivaldi user...

I really am NOT seeing any significant changes in the document inspector or other tools apart from moving stuff around for no reason other than to break muscle memory.

The pie chart on the network breakdown does seem to finally be fixed and not be dropping the ball on flat out refusing to see large amounts of loaded assets on a number of sites. Since the content it often missed was loaded via scripting, I would assume this change is part of the new scripting engine.

I do notice a LOT of <select> type menus in add-ons appear to be broken, the dropdown/flyout appearing at the bottom of the display and nowhere near the control.

It's still new enough that I'm waiting to see how bad things go bits-up face-down with it. I have an inherent distrust of FF in terms of memory hogging, instability, piss poor UI design... It has never been a browser I recommended for anything more than use as a development tool, particularly with how FLOSS fanboys gushed over everything about it and refused to admit its shortcomings -- to the point of "it's not a bug it's a feature" being their rally cry.

So they've got a lot of burned bridges to mend with me as a user.

I wonder if they fixed bugzilla 915, or will that one stick around until it is old enough to drink? Nothing like slopping in HTML 5, CSS3, and ECMAScript 6 when they don't even have HTML 4 and CSS2 complete.

Everybody says the new Firefox is fast, but when I load up sites on my computer it's not faster than the old Firefox was, and definitely not faster than any other browser I can run on the same hardware. The initial load feels fast, but it feels like they're throttling JS events or something - anything that listens to events to do anything related to CSS brings the browser to a crawl!

This week I spoke to Firefox developers and they said I found a regression (yay me) and 2 bug reports were filed. It seems perhaps they do something 2x as often as they need to during the processing of CSS, and for some people there's little difference, but for me for example pages that get 40-50 FPS (rendered frames per second) in Chrome will get 1-2 FPS in the new Firefox, like running at 1/25th-1/50th the performance of other browsers.

• bugzilla.mozilla.org/show_bug.cgi
• bugzilla.mozilla.org/show_bug.cgi

Hopefully they can fix this, Firefox is the only browser I have to lose work time trying to help them file report bugs for.

Quantum is allegedly faster and takes less memory. The page title is "2x faster and 30% less memory". That's far from true, in my experience. Before, it took between 400MB & 500MB with just a single process. Now, it's split into multiple processes. One tab open and I see at least four processes, each taking between 150MB and 300MB, for a collective total of around 750MB . As far as speed, hard to say. I have a fast connection, so Firefox has generally been fast with it being noticeably slow on Facebook. It's still slow on Facebook, and I blame Facebook for that, not the browser. I definitely wouldn't say 2x faster, and instead of 30% less memory, I'd say 30% MORE memory.

Here's my standpoint. I've been using the preview of Quantum (ie Firefox nightly) for a few months, in parallel with Chrome and Canary. (caveat: I'm not doing any front-end dev, so the grid-inspect which is supposedly awesome don't really get my excited ;-)

So far I like it a lot. I have too many years of habits in Chrome to make the switch completely, but I do use both at the same time on a daily basis.

Here are a few features I do love in the new Firefox:

• Container tabs! Because I'm paranoid, I have several google accounts to have several Chrome profiles, so that I get segregated context for personal stuff, work stuff, production stuff, and personal but serious stuff (banks, ...) Firefox introduced "containers" which are separated context so that no cookie, history, localstorage or anything personal is shared between these containers, but you can manage this under s a single firefox account, with a single set of extensions, bookmarks, ...
• Tracking protection enabled by default, everywhere. (I do use uBlock, privacy badger, and uMatrix on Chrome, but having this built-in the browser feels good)
• native "reader" mode to remove the shiny stuff. No need to add an extension (I'm still amazed Chrome don't have this natively)
• send the tab to another device. Awesome to share stuff between home and work or mobile!
• embedded Pocket (I read a lot on the go, especially in the subway where data is not available everywhere, so I'm a big Pocket user). No need to add an extension
• native webpage screenshots, no need to add an extension

I would not say it's a game changer and people should switch.

But I would still recommend to people to give it a try. It's a really modern and fast browser, and I wouldn't be surprised to more people adopting it. Especially with all the privacy concerns that keep increasing. Using Firefox+Duckduckgo as a default search engine (duck duck go has improved a lot imho over the last years), gives you a good and easy starting point.

I use FF 57 for some weeks (shortly before it entered the beta phase) and as a long time user of Chrome I switched back to FF (last Version I used was 3 or 4). I'm pretty happy with performance and the new UI. The DevTools are a bit buggy but surely it will be fixed in the next versions.

(written with FF 58b4 ;) )