By Craig Buckler

Firefox 4.0: Week 1 Review

By Craig Buckler

It’s been a frantic couple of weeks in the browser market. Microsoft released the highly-anticipated Internet Explorer 9.0 on March 15 followed by Mozilla’s release of Firefox 4.0 eight days later. Firefox was downloaded 5.5 million times within 24 hours — more than twice that of IE9. But, Mozilla’s browser can be installed on more operating systems and the number fell short of the 8 million who downloaded v3.0 on day one.

In our poll last May, Firefox remained the web developer’s choice of browser but Chrome had started to encroach on its territory. Can Firefox 4.0 win hearts of developers and users alike?

Firefox 4.0 Installation

Firefox is available in more than 70 languages and the desktop browser can be installed on Windows, Mac OS or Linux.

The Windows installer is 11.8MB — 50% larger than the previous version. However, it’s a self-contained file and, effectively, far smaller than the background file downloads required by IE9 and Chrome. Upgrades from v3 are painless and installation should take no more than a minute or two. No reboot is necessary.

Firefox 4.0 Interface

Firefox has been overhauled; it looks great and existing users won’t be disorientated by the new interface. The most noticeable changes are the new Firefox button, no menu, and tabs above the navigation bar. Mozilla has undoubtedly copied the best UI elements from other browsers but that’s no bad thing.

Firefox 4 screenshot

The Opera-like menu button shows provides access to the most-frequently used options but several improvements are evident in Firefox’s implementation:

Firefox 4 menu

  • The 2-column layout is clearer and easier to use.
  • Although it can still be enabled, you’re unlikely to miss or require the menu bar (I often keep Opera’s menu in view to access features such as Dragonfly).

Tab fans will love the new functionality. Firefox implements application tabs: an icon-only tab can be ‘pinned’ to the left side of the bar. However, like Chrome and Opera, you cannot ‘unload’ an App Tab with a middle click — it’ll always reload that page on start-up. Fortunately, some add-ons such as Tab Utilities allow that behavior so the pinned tab remains, but it’s dimmed out and won’t automatically reload.

Panorama allows you to organize tabs into related groups.

Firefox 4 Panorama

I initially found Panorama a little confusing and buggy when used with Windows 7 taskbar previews. That said, I’m beginning to see the advantages. Opera’s tab stacking is easier to use, but Panorama is more powerful than Speed Dial or an about:tabs page and groups can be hidden until they’re required.

Like its competitors, Mozilla has removed the status bar and you’ll just see a discreet URL at the bottom of the window when hovering over a link. If you have an extension which required it, you’ll need to enable the “Add-on bar” — essentially, a less-functional status bar. Personally, I think Mozilla should have kept the status bar but hidden it by default.

The remaining modal information dialogs have been consigned to the browser bin. For example, JavaScript alert boxes can pop-up on any tab and won’t require your immediate attention.

I also liked Firefox’s new activity indicator. It spins anti-clockwise when connecting, then clockwise when downloading. It’s a nice geeky touch which could also help when debugging connectivity issues.

Finally, if you don’t like the way Firefox looks, almost every part of the UI can be configured. Themes, the background image (personas), bars, icons and tabs can be added, removed and rearranged at will.

New Features in Firefox 4.0

Mozilla is in an enviable position: they rarely need to add functionality because their browser supports thousands of third-party add-ons. While other vendors scramble to create decent developer consoles, Mozilla can relax because no one’s managed to beat Firebug.

Amazingly, the majority of good extensions work in Firefox 4.0. I didn’t experience any add-on quirks … although you could. The add-ons manager now appears its own tab:

Firefox 4 add-ons manager

With the exception of UI tweaks, the main new features are:

  • Improved privacy controls.
  • The new Web Console (see below).
  • Firefox Sync, which allows you to synchronize bookmarks, passwords, preferences, history and open tabs across multiple devices. It generally works well and even appeared to synchronize about:config settings, although you may notice a few omissions such as cookie exceptions.

Like IE9, Mozilla has demoted RSS to a secondary feature. The glowing orange icon has gone, but an RSS button can be added to the toolbar and there are several add-ons which bring back or enhance the functionality.

Firefox 4.0 Performance

Firefox 3.x was criticized for its speed. While some problems were caused by add-ons, the browser felt sluggish compared to newer versions of Chrome, Safari, Opera and IE. If you abandoned Firefox for that reason, you’ll be pleased to hear that v4.0 has been radically improved. On my main PC, a cold boot of Firefox 3.6 could take up to 30 seconds — Firefox 4.0 with the same extensions takes just 5 seconds.

If you look around the web, many of the recent benchmarks have been confusing — if not contradictory. In my experience, the performance difference between the top 5 browsers has become almost negligible. Firefox starts a second or two slower than IE9, Chrome and Opera but it’s not enough to cause exasperation. Page rendering and JavaScript performance is good but, although Firefox implements graphics hardware acceleration, it’s not noticeably faster than its competitors.

With regard to memory usage, Firefox 4.0 seems a little more hungry than v3. If you only open a few tabs at a time, IE9, Opera and Chrome normally use fewer resources. However, open a few more, and Firefox’s single process becomes more efficient.

Stability is as good as ever. I experienced a couple of interface rendering quirks, but nothing untoward occurred.

Firefox 4.0 Web Standards Support

Only the most radical web developer could complain about standards support in Firefox 3.6, but a number of new features have appeared in Gecko 2.0 to help it keep up with advances made by webkit and Presto (Opera):

  • additional support for HTML5 audio, video, forms, file handling, and drag and drop.
  • support for the new WebM video format
  • WebGL and 3D graphics
  • CSS3 transitions and transformations
  • SVG for backgrounds as well as images

Mozilla has announced plans to adopt a Chrome-like update schedule so we can expect new technologies to appear rapidly.

Firefox 4.0 Development Tools

If we disregard add-ons for the moment, a naked Firefox provides a basic source viewer, Error Console and a new Web Console. Essentially, the Web Console is a combined log of all net activity, JavaScript and CSS errors which sits at the top of the browser window:

Firefox 4 Web Console

Unlike other consoles, it displays file downloads and errors as they occur: interesting, but rarely essential. Overall, I found the it a little ugly, clunky and slow — especially compared to the other improvements Firefox offers. It could be useful if you had nothing else, but you wouldn’t climb over Firebug to get to the Web Console.

Fortunately, we’re spoiled for choice when it comes to developer tools. Our lives would be far more difficult without Firebug, Web Developer, Console2 and others.

I hope Mozilla continue to provide technical and financial support for these add-ons; they have made Firefox what it is today.


I hadn’t expected to be so impressed by Firefox 4.0. Mozilla has taken the best features from other vendors, improved them, and created a slick, cohesive browser which is easy to use and available on all popular operating systems.

Firefox 4.0 good points:

  • Attractive, usable and customizable interface with superior tab handling
  • Significant speed improvements over Firefox 3.x
  • Great features for developers, power users and novices
  • The best choice of browser add-ons

Firefox 4.0 bad points:

  • The latest versions of IE, Chrome and Opera are just as fast, if not faster in some respects. Mozilla will need to keep up
  • It may take a little time before all your add-ons work on Firefox 4.0
  • A few minor UI bugs
  • Web Console looks like an afterthought and lacks polish

I have no hesitation in recommending v4.0 to existing Firefox users, although you should check essential add-ons are compatible. If you abandoned version 3.x because it was slow, you should also give Firefox 4.0 a try.

In my opinion, Firefox remains the best application for web development but it’s also great for casual browsing and I’m not using other browsers as much as before. If you find IE, Chrome or Safari too limited and Opera too daunting or quirky, Firefox occupies a middle ground that’s ideal for a wide range of users.

Nearly 50 million people have downloaded Firefox 4.0 — you can follow them at

  • Rjs37

    I actually preferred the layout from Firefox 3. Lumping all of the menu together into a single button was irritating to say the least. It now takes 3 or 4 clicks to do things that used to require 2. Such as re-opened a closed tab.

    And I’ve also moved the tabs back down below the address bar too. Much more logical placement imo. There’s some bits I like and it does feel faster but some of these UI Improvements for me aren’t improvements at all for me.

    • Fair enough, although I rarely find myself needing the Firefox menu or the old bar. Fortunately, you can configure Fx4 to look and act like Fx3 — or any other browser for that matter.

    • Jonathan

      You can re-open a tab by right-clicking on the tab bar, and choosing ‘undo close tab’ – that’s only 2 clicks :-)

    • joel

      Since you mentioned it specifically, Ctrl-Shift-T will re-open the most recently closed tab. Keep pressing it and it works back the list. I’d even forgotten that there was a menu option for it. :P

    • florin


      I am really glad your opinion is in minority regarding the new menu functionality. Most of us, and I believe that this is the majority, prefer minimalist, less cluttered interfaces without losing features, hence the “lumping”.

      What would I use of that menu and how often anyways?
      The address bar is also placed fittingly with a corresponding tab. The url matches the tab. Did you notice that each tab has its own history? So that back / forward buttons are placed rightly too.

      The search bar and the other buttons then, are consequential and not disruptive.

      Congratulations for the thoughtful and ergonomic design.
      The add-on bar is a pain to reclaim once closed. Fortunately I found a plugin (barlesque) that conveniently tucks it to the right bottom corner.

      Memory usage remains the ugliest discomfort.

    • Rjs37

      Thanks to those providing quicker ways to re-open closed tabs. I’ve decided to try using the button again for now (against my better judgement). I’ll see if I can get used to it.

      In that particular instance I just feel that they’ve improved aesthetics (can’t deny that the button looks better than the old menu bar) at the price of worsening the usability. Quite a few things though now take longer to do because it’s all hidden away behind an extra layer.

      I guess they don’t feel usability to be as high a priority.

  • Aaron

    I think I am going to wait before I download FireFox4. As you mentioned something about addons not working on it.

    • Not all add-ons are compatible so you should check first. However, you may be able to drop a few if features are natively supported (such as bookmark sync).

  • Xzyfer

    I’m curious to know why people consistently say Firefox it the best development browser?

    I personally was an avid Firefox user before adopting Chrome at about version 4. There is personally nothing I miss from Firefox in Chrome.

    * The webkit inspector (different in Chrome 10 that Safari 5) is comparable to firebug.
    * The webkit profiler is a fair substitute for ySlow.
    * There is a web developer tool bar port for Chrome, but there are many alternatives as well.
    * Chrome 10 has comparable, if not better, standards support (correct me if I’m wrong), and scores higher the both IE9 and Firefox 4 on HTML5Test (

    What am I missing? Does is simply come down to personal preference?

    • Xzyfer

      I also forgot to mention that Chrome has high compatibility scores than all other current browser versions on Can I Use (

    • While there’s nothing wrong with using Chrome for development, Firefox offers a richer set of add-ons which have a deeper level of browser integration.

      It also comes down to personal preference too. Firebug and the WDT have been around a long time so developers have become attached to them.

    • Armen

      I love Chrome and use it a lot, but there are two things I miss – ability to disable cache and ability to quickly turn on/off javascript.
      Ironically, those two options currently are broken in Web developer toolbar in FF4 :)

      • Stormrider

        I use Toolbar Buttons (an addon) – it gives you buttons to toggle JavaScript and toggle CSS – 2 buttons I use a lot!

  • Jon Penny

    The thing with Firefox 4 which disappoints me the most is that it still takes up a large amount of memory on my machine. I only have a couple of add-ons installed such as Firebug and the Web Developer toolbar. I still find that after a few hours of having the browser open I have to close it and re-open it again which is a little annoying.

    Anyone else having this issue at all?

    • It depends what you mean by large. I’ve had Fx4 open all day and it’s currently consuming 270MB of RAM with 8 tabs open. It seems that the first few tabs use more RAM than Fx3, but Fx4 then becomes more efficient.

      It’ll depend on your OS and add-ons too.

    • Aankhen

      Yeah, Firefox 4 is a major step backwards in stability in my experience, and with fewer addons installed at that. I thought FF3.6’s 800 MB (memory usage) with 150 tabs was ridiculous, but FF4 is at 1.3 GB as I write this with 124 tabs. The best part is that it slows to a crawl after ~50 tabs, and I get frequent crashes. No, wait, the best part is that when it crashes, the “Crashed Session” is useless 9 times out of 10: either it restores the correct number of tabs and leaves them blank, or it restores the session and crashes immediately. (To be fair, that’s probably Tab Mix Plus’s fault, as I’ve disabled the builtin feature.)

      Colour me sad. I’d really been looking forward to improved performance and reliability, along with the lovely hardware-accelerated, antialiased rendering and improved UI.

    • You have 150 tabs open? And I thought I opened a lot!

      Have you tried using panorama to group and hide some? Does it make a difference?

      • Aankhen

        Yeah, I tend to open a lot of tabs every day when I go through my feeds… I open everything that looks interesting, then work my way through the lot afterwards. Plus there’s stuff left over from previous days, so it kinda builds up. :-)

        I haven’t used Panorama as yet. I thought it only hides them, but they’re still kept in memory, ready to be called up at a moment’s notice?

      • Alan Jay Weiner

        I’ve had over 360 tabs open simultaneously, in 3 windows. I tend to open a lot of tabs to read later.

        Right now I have ~12 tabs for my web host, ~15 tabs of web-dev references, another ~10 articles to read, ~20 pages of my site, 1 gmail tab with another 8 from URLs in emails, and another tree of ~25 tabs because I saw a message about FPGAs and networking stacks and found a lot of interesting things to read later.

        Another window has ~70 tabs with Android development stuff.

        I’ve had enough tabs that Firefox crashed, then repeatedly crashed as it tried to restore them all (that’s the 360+ tabs…)

        I’ve since installed Load Tabs Progressively; so far that’s working fine.

        I bookmarked a tree of ~200 tabs of home-theater stuff; about evenly split between info about equipment and home-theater chairs.

        That’s really fairly typical for me.

        I’ll wait another couple of weeks before moving to FF4 to let add-on glitches get fixed. I’ve got a lot of them loaded too…

  • Armen

    Seeing rapid update cycle of Chrome and Mozilla’s plan to switch to the same model, I can’t stop thinking that IE9 is already obsolete.
    Seriously, after watching all those ass-kicking demos in Mozilla’s Web-o-wonders, now I’m sure as never before that IE should go. Microsoft’s browser project should be closed and forgotten as a biggest failure of web. Period.

  • Mike B

    One key problem with Firefox 4 is the lack of a RSS button. After many members of the Firefox and the Web community complained after it was removed from the main UI due to “lack of use”.

    • Aankhen

      You can add the button to the Navigation Toolbar by right-clicking on it and selecting Customize. (I realize that this does not aid discovery; just a tip in case you weren’t aware of it.)

  • Dave

    Does anyone know how to create a single site browser from FF4?

    The save this website as an application was a favorite feature of mine in FF 3.X and I cannot for the life of me figure out how to get Prism(or its functionality at least) back!

  • Soluweb

    We have used FF in some PCs and have found that takes a lot of memory, but renders really fast and most of the plugins are working fine.

  • Mathieu

    Firefox button has these problems:
    1. Accessing an item in the right column often brings up the sub-menu from the left column. Particularly, heading the mouse for the Add-Ons item brings up the Edit sub-menu, so it takes some work to avoid this. Usability says more of a delay in the pop-up of the sub-menu is required.

    2. I miss the Tools menu. Perhaps items have been re-allocated in the Firefox button, but I have not found them all yet.

    On the plus side, I can hit “Alt” to make the menu bar appear temporarily. This works for me, although some people will want to use Options > Menu Bar to use it in place of the Firefox button.

  • Milan Petrovic

    Firefox 4 is a big step forward for the browser, but it’s still not enough, and they still lag far behind Opera and Chrome in both performance and stability. I use Firefox for development only, since for what I need from web browsing Firefox is not usable.

    In Opera right now I have 55 tabs opened (stacked in few stacks), and Opera uses 460 MB of RAM with all that. I tried to open same pages in Firefox 4 and after 30, Firefox regularly crashes or eats too much memory. Chrome in some things does even better job than Opera and manages to handle large number of pages open. Also, I have Opera running without restart or crash with all those tabs open for last 23 days (my computer runs non stop). I like to see anyone to do that with Firefox. Also, panorama view with 20 or more pages inside can take forever to display (I have Core i7 Quad CPU with 8GB RAM), making it unusable and defeats the purpose of using it in the first place.

    All development related problems Firefox 3.6 had, are still present in Firefox 4, but not as pronounced. But, I still have same problems: memory leaking, random crashing, JavaScript problems, and I have to restart it every couple of hours even with 3-4 tabs opened in the same time.

    No matter how big leap Firefox 4 is from Firefox 3.6, that is not good enough. Mozilla needs to stop adding features to Firefox, it needs to make it fast and stable, not faster or more stable that previous 3.6 and be satisfied with that.

    • florin

      Improvements are always a hot pursuit and I can see many places where Firefox can improve.

      But to say that Firefox 4 is unusable for browsing is a stretch. C’mon, where were you 2 or maybe 6 years ago? Unusable? The browser on my phone is no fun yet still usable.

      Memory size yes, a concern.

      Unusable? Give’m a break.

  • Kim

    My biggest beef is that I used to use Ctrl+Shift+E 50 times a day to open Web Developer Toolbar’s Edit CSS window. FF4 co-opted that keyboard shortcut and it can’t be changed. Annoying.

    Oh, and Roboform6 and FF4 don’t play nice together.

    Still, I’ll learn new patterns and continue to use FF.

    • chris

      I used keyconfig to change Edit CSS to point somewhere else. Couldnt seem to change group tabs, but at least you get your edit css back, even if you will still press the wrong thing for a while

  • PCHuprina

    Not sure I like Firefox at all. Please review a issue I was having with it have some type “jiggle” upon a slide show image transitions: has basically turned me off it, know I have to test it, but now leaning to Chrome for dev/design work

    Many thanks to Paul O’B to helping me solve the problem in the forum.


  • Patrick Samphire

    I’m using FF4 on a Mac, and I can’t say I’ve noticed any particular improvement in speed since 3.6. Additionally, I’ve encountered a few slightly obscure rendering bugs, and a some minor bugs with the browser itself (for example, I have checked for FF to warn me if I’m closing multiple tabs, but it doesn’t).

    I also wish they had gone the same way as Chrome and IE by amalgamating the search and address bars.

    And, finally, I find having the refresh button between the address and search bars really counterintuitive. It’s far easier to go to the far left (or far right) with a cursor rather than aim for somewhere in the middle. (Yes, I know Safari has the refresh in the same place, but I almost never use Safari.) The home button on the far right equally irritating. It goes against all the normal conventions, and is just unhelpfully weird.

    If it wasn’t for Firebug and WDT, I doubt I’d use FF at all any more.

    • It’s taken me a while to get used to the stop/refresh being at the end of the address box. However, you can move it elsewhere by customizing the toolbar.

      • Patrick Samphire

        Okay, I’ve figured out how to do that at last. Not intuitive, to say the least!

    • Alexandre

      There is an extension for mergin the address and search bars which works great (Omnibar) and was available for FF4 on the day of its release.

      There is a quirk with the multiple bars warning however, which just needs a one-time update of an option directly in about:config.

      You can also merge the refresh and stop buttons (extension I think) or just move it where you please.

  • CodeMyConcept

    We are so excited with this release, but all the people out there using IE remember the mission to get IE6 to 1%, this would made the world a better place!

  • CookieJamster

    Firefox allows you to unload an App Tab with a middle click. The pinned icon remains, but it’s dimmed out and won’t automatically reload when the browser’s restarted.
    Sounds great! Except, you seem to be describing a feature which doesn’t exist. If I middle click, the App Tab is closed altogether, just like any other tab. Have you mistaken an add-on’s behaviour?

    • Crikey, you’re right. Sorry about that. I suspect it’s a feature (or quirk) of the Tab Utilities add-on, although there’s nothing in its options to suggest it handles App Tabs.

      Therefore, Firefox’s default App Tabs act in the same way as Chrome or Opera. Shame. I’ve updated the article accordingly.

  • Mathieu

    Panorama (tab groups) did not last through a shutdown and reboot for me. I’ll have to see if bugs have been reported on this. Perhaps because I don’t have Sync set up yet?

    • Mathieu

      I found reports that one needs to have “browsing history” on and “show windows and tabs from last time”. I guess that makes sense. Some indication of this interaction when setting up tab groups would be nice. Since Panorama (tab groups) appears as a window outside of the normal tab display (and has an unrelated name), it is not obvious that this relates to history and tab settings. In Opera, tabs and tab groups are obviously related in how they are displayed.

  • Seedplanta

    Ok, so apparently I must be with the approx 1% or so who scrambled hard to get Fx3.x back, because Fx4 was slower than my 3.x and i posted on Fx forum but still heard no feedback, im beginning to get jealous as e’ry1 else seems to have experienced Fx4’s faster speed. I was cool with all the other updates, tho i did quickly reenabled the status bar tho it is less feature rich…but im wonderin why Fx4 was slower on my pc with same extensions (all but 2 were compatible with 4). Any help is appreciated.
    Panorama sounds interesting, but didnt find it in the addons section, assuming its not compatible with Fx3.6, already switched bak, after 2 days i couldnt take the irritation from Fx4 anymore.

  • Arkh

    “On my main PC, a cold boot of Firefox 3.6 could take up to 30 seconds — Firefox 4.0 with the same extensions takes just 5 seconds.”
    My FF3 appeared the second I clicked on its icon. The trick ? SSD.

  • the old rang

    I have been using (and prefer) the Netscaps/Firefosx browsers since they first came out (either/both of them)
    I have differences with your assessment.
    I figured our how to make it almost look right, I don’t like Opera/Chrome, so, If I wanted a browser to look like a cell phone, I would buy a cell phone. I don’t. Between Chrome, IE and Opera… I prefer a pencil.
    Mozilla could have made these improvements months ago, but didn’t.
    They could have had 3.x running with a faster Java (the only real plus in my book), but waited for the ‘new’ edition.
    Looking at what is going on in the plug-in area, they are fighting against any that slows the loading (Computers being what they are, there are interesting choices. Have a faster loading security sieve like IE (No one has yet actually shown it is safer…. as long as it has an ACTIVE X Backbone… as the boo boo on day one positively showed. Patches are NOT FIXES… especially when you forget to put them in…, or needless frou-frou to please, I have no idea.)
    A lot of the plug ins will never be back, it seems… I miss Dilbert…
    But, I will keep 3.6 for a while. (Loading 2.6.38 Kernel sped much of the items – I use Linux/Ubunt, BTW) I keep 4.0 in a folder, just in case I really need or want the ‘java’… But, didn’t see anything else really worth the upgrade.
    Especially their ChromeoOperetteo interface… I want to browse the net, not make a phone call.

  • AnilG

    There’s always a lot of criticism with change. I feel like folks like to criticise FF sometimes.
    I’ve never had a problem with speed or bloat, but I remember running JS heavy sites off FF in 2004/5 when IE6 wouldn’t even run them (crashes).
    Some of my extensions are not ready for 4.0 yet so my work machine is still on FF 3.
    I can’t understand why anyone would leave FF for Chrome for development, maybe I haven’t tried hard enough with Chrome.
    Hoorah for Firefox. It’s a legend in the history of the web and still the best browser on the planet.
    BTW I can’t get Bookmark Sync to work but XMarks never fails.
    I can’t see a Firefox button but maybe that’s the Mac version?!
    I never lost my menu bar but maybe it picked up my preferences on upgrade?

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