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Firefox 5 Benchmarked – Faster And Better Than Ever Before!

By Ricky on June 21st, 2011 

Officially, Firefox 5 is scheduled for release tomorrow. However, users of the beta channel have already got their hands on it. One of the promises for Firefox 5 is better performance. We took tested Firefox 5 and benchmarked it against two other browsers - Google Chrome and Opera. We used the latest version of Google Chrome from the beta channel and the latest stable version of Opera - Opera 11.11.

SunSpider JavaScript Benchmark

The SunSpider JavaScript Benchmark is a test for the JavaScript engine of the browser. In this benchmark, lower scores (time) means better performance. In our earlier benchmarks, Firefox is always slower than other browsers such as Chrome and Opera. Let us see how well Firefox 5 does.

As you can see from the graph above, Firefox 5 has made huge improvements in its JavaScript engine. It is now much faster than both Chrome and Opera. However, the difference is very small - just 30ms faster than Chrome and 8ms faster than Opera. So, finally Firefox can no longer be considered a slow browser.


Peacekeeper is yet another highly regarded test for the JavaScript engine. Unlike the SunSpider test, Peacekeeper tests the normal JavaScript applications such as animations, navigation, forms etc. In this test, higher scores means better performance. Here is the result:

The result from the Peacekeeper test is very different from that of the SunSpider test. Here, Opera got the highest score while Firefox 5, which did best in SunSpider, performed the worst of the three browsers.

HTML5 Test

The HTML5 Test is a test to determine how many of the HTML5 and related specifications are supported by the browser. It does not test how well the specifications are supported. Scores are awarded for support of the HTML5 standards and bonus points are awarded for supporting related drafts and specifications. Higher scores are preferred in this test.

In this test, Chrome takes the lead by scoring more than 300 points. Opera and Firefox are neck to neck with Firefox scoring 254 and Opera scoring 255. The performance of Firefox 5, is a huge improvement from that of Firefox 4 which manages a score of just above 200.

Cold Start Time

This is the time it takes for a browser to start on a machine that has been just restarted. Once the machine has finished loading everything, the browser is restarted and the time it takes for it to load a locally stored file is found out. Obviously, lower cold start time is preferred. Here is how the browsers performed:

Opera takes the longest time to start here at around seven seconds. The other two browsers have almost the same cold start time at a little above four seconds.

A test for warm start was not done because all of the three browsers have a warm start time of less than a second and it was impossible to time it properly.

Memory Usage

The different browsers takes up varying amount of RAM. To test how much each of them is taking up, we loaded 25 popular websites and check the memory consumption of the browser after opening every five websites. Extensions, add-ons etc. which are not installed by default are removed. Here is the result:

The result here is staggering. While Chrome takes up more than 1GB of RAM on opening 25 websites, Opera and Firefox takes up a little more than only 400 MB. Firefox and Opera takes up nearly identical RAM throughout, although Firefox takes up a little bit less than Opera.


As you can see, Firefox 5 does very well in four out of the five tests. Here are some of the main points about Firefox 5 from the tests:

  • It has a very fast JavaScript engine (according to SunSpider test)
  • It has much improved HTML5 support compared to Firefox 4
  • It has a very fast cold start time comparable to that Chrome
  • And finally, Firefox 5 takes us minimal RAM even with 25 websites opened.


1. SunSpider 0.9.1 Benchmark

2. Peacekeeper Benchmark

3. HTML5 Test


Firefox 5 Benchmarked – Faster And Better Than Ever Before! was originally published on on June 21, 2011 - 1:15 am (Indian Standard Time)