Composite Scoring
Overall memory efficiency is gauged by the difference between a browser's single-tab memory usage and final -39-tab memory management total. The browser with the lowest score is able to return the most physical memory back to the operating system without actually closing the application itself, but simply by decreasing workload (closing tabs).

Chrome takes the lead for memory efficiency on both operating systems, as Firefox takes second place on OS X and IE9 takes second under Windows 7. Third place on OS X goes to Safari, while Firefox takes third on Windows 7. Opera finishes last on both platforms.
Drill Down
The charts below are for the single-tab and 40-tab memory usage tests, followed by the -39-tab and -39-tab plus two-minute memory management tests.
The three cross-platform browsers all report approximately double the memory usage on OS X than on Windows 7. Firefox only gives back about one-third of its 40-tab memory usage total on OS X, a sharp increase from Windows 7.
- The Top Four Browsers, Tested And Ranked
- Chrome, Firefox, IE9, Opera, Safari
- Test System Specs And Software Setup
- Test Suite And Methodology
- Start Time
- Page Load Time
- JavaScript Performance
- DOM And CSS Performance
- HTML5 Performance
- Hardware Acceleration Performance
- Plug-In Performance: Flash, Java, Silverlight
- Memory Efficiency
- Reliability, Responsiveness, And Security
- Standards Conformance
- Test Analysis
- OS X And Windows 7 Winners' Circle




When we have more [official] stable 64-bit browsers, I'll definitely do a 64-bit WBGP - including versus their 32-bit counterparts.
Nearly every performance benchmark there is points in that direction. This probably has a lot to do with how much time developers spend optimizing for Windows - after all, Windows holds 90+% of the desktop user base. However, it is interesting that the rift between Windows and OS X is far greater than between Windows and Linux for the core stuff like JS, CSS, DOM, page loads, etc. Plug-ins are another story, they're always much better on Windows than the other two platforms.
(The nice popular ones like ABP, Lazarus, Greasemonkey all have equivalents; some lesser-used plugins like Rikaichan also have ports by now. Only a matter of time!)
as always, a great read.
All versions of Chrome hold up incredibly well cross-platform, if you look back at the two Linux WBGPs, it won there, too. Thanks for reading!
Absolutely, a Windows 8-based WBGP is already in the cards for October.
When we have more [official] stable 64-bit browsers, I'll definitely do a 64-bit WBGP - including versus their 32-bit counterparts.
Testing these browsers at stock doesn't reveal even an eighth of the picture.
btw great work adamovera keep it up man
Interesting idea, so basically a tweaked-out edition of the WBGP, where we use all the tools available to each browser for performance gains... That could work, but I gotta warn you that the next three WBGPs are already decided, so it would probably be real late in the year, or even next year before I could get to it.
Nearly every performance benchmark there is points in that direction. This probably has a lot to do with how much time developers spend optimizing for Windows - after all, Windows holds 90+% of the desktop user base. However, it is interesting that the rift between Windows and OS X is far greater than between Windows and Linux for the core stuff like JS, CSS, DOM, page loads, etc. Plug-ins are another story, they're always much better on Windows than the other two platforms.
The big problem with including the dev channel browsers is the amount of time it takes to produce the article (testing/charts/writing/editing/translating), combined with the tendency of the dev channel to constantly update. Before testing is even completed it's certain that something will update. TBH, the stable channels of Chrome and Firefox are a handful as it is. For example, for this article I had to test 8 browsers (4 on each OS), but I ended up testing 18+ due to OS X, Chrome, Firefox, Opera, Flash, and Java updates. Sorry, but I'm just not sure it's even doable in this format. Thanks for reading!
well I wanted to include it in my comment myself but I forgot I wanted to say if the timing allows
My computer is fast enough that it does not really mater what browser I choose.
In my case, ease of use means that I can see what is going on.
I decry the trend towards dumbing down the UI on every program I use.
(I also refuse to call software 'Apps', to me an app is a mini-program on a phone.)
I always turn on all menus, buttons and labels in WaterFox.
BTW: Good point.
Why don't you include WaterFox in your testing?
It is the 64 bit version of FireFox and I am sure that in your speed tests it may do a little better.