Mozilla Links has an article about the Firefox ultimate feature - Performance, in which they compare the JavaScript performance on different web browsers. Firefox 3 beta 4 as some really impressive JavaScript performance and outruns Internet Explorer 7 with about 700%.

But the article did not test Internet Explorer 8 beta, which I think should have been there (at least for reference). Since the IE8 team claims the performance is so much better, and my feeling after a few days of IE8 usage says so I had to do some testing on my own.

I used the same JavaScript benchmarking tool that was used in the article - SunSpider JavaScript Benchmark.

The results was not as I expected - yes, I did expect IE8 to perform better!

IE8b1 vs FF3b4 JS performance

The results show that Firefox 3 beta 4 performs 2-3 (or more) times better than Internet Explorer 8. It’s an improvement since IE7, but not as good as I was expecting.

Now we have to consider that this is the first beta of IE8 and its beta 4 of Firefox 3, which means that we will see some changes in this test in the near future. Just look at the graph in the article and see the improvement from FF3 beta 3 to beta 4, about 200%.

Worth to notice is also that the script running times with IE8 was steadily increasing!

Another interesting thing is that Internet Explorer 8 had a test deviation of about 60-70% while Firefox 3 had about 20%.

I did the test on my Windows Vista Ultimate SP1 machine and run the tests on clean browsers one test at a time and then switched browsers.

I think it is great that the two major browsers get heavily improved JavaScript performance in their upcoming versions, especially Internet Explorer which really sucked on this point.

On the other side, I consider myself an optimization nerd sometimes and really like to do high- and well-performing JavaScript coding. This will not be that visible anymore :-(