http://www.tomshardware.com/reviews/chrome-27-firefox-21-opera-next,3534-12.html
Performance Index
The data in the chart below is a geometric mean of all four performance-based categories: Wait Times, JavaScript/DOM, HTML5/CSS3, and Hardware Acceleration.
Firefox 22 pulls off an upset, replacing the long-time performance champion Google Chrome as the new speed king! Google doesn't lose by very much though. In fact, if we moved the decimal point and rounded, this would show up as a tie. Meanwhile, moving on to the next win-eligible browser, IE10 is far behind in third place, with less than half the performance score of Firefox 22 or Chrome 27. Opera 12 is in last place, lagging slightly behind IE10.
Non-Performance Index
The data in the chart below is achieved through the geometric mean of all four non-performance categories: Memory Efficiency, Reliability, Security, and Standards Conformance.
Firefox manages to conquer this category thanks to a stellar finish in proper page loads as well as strong scores in all three remaining non-performance categories. Chrome 27 finds itself in a comparatively distant second place. Its terrible page load reliability, combined with tighter scoring in the other metrics, sink Google's chances. IE10 is around 15% behind Chrome in third, with Opera 12 landing in last place with a score of less than half that of Firefox 22.
WBGP XVI Champion
Now we combine equal parts performance and non-performance metrics, stir, and taste...
With no apparent weaknesses and generally strong finishes all-around, combined with near-native start times, greatly-improved hardware acceleration scores, and almost-perfect reliability, the latest version of Firefox soundly wins this installment of the Web Browser Grand Prix.
While Chrome 27 is the leader in most categories, Firefox 22 is right on its heels in second place. So, with close second-place finishes in nearly all categories that Chrome wins, Mozilla really needed to exploit any weakness in Chrome. And it does just that. Chrome's extreme fall from grace in start-up time really hurt. With Firefox attaining top marks in that category, an extreme divide is created where we'd normally expect both browsers to pace each other. The same type of brutality is used against Chrome in reliability testing, where Firefox 22 almost pulls off a perfect score, while Chrome 27 has issues with more than 25% of the workload.
Although this is not the first time that Firefox has edged out Chrome, this is the most punishing margin of victory. It's as if Mozilla knew just where to strike. Now, the onus is on Google to either completely outpace Firefox in performance (as it once did), or focus on addressing Chrome's own weaknesses. Either way, Mozilla buys Firefox some time at the top.