I tested four browsers with the SunSpider tests and it turns out that Firefox 5 was faster than Chrome, Safari and Opera. This was quite surprising to me as it beat out Chrome but quite a bit. It’s also interesting how far behind Safari is.
Opera 10.5 – 534.0ms +/- 1.4%
Chrome 12 – 524.6ms +/- 4.6%
Safari 5.0.5 – 566.9ms +/- 4.2%
Firefox 5 – 448.8ms +/- 0.9%
Now the tests aren’t scientific by any means, but they do represent my computer on a normal day. I’d suggest you run them for yourself and see what you come out with.
It’s also good to note that Firefox 5 had no extensions running, Chrome had 7, Safari had 2 + Glims and Opera had none. This could change the output but really shouldn’t have an effect.
I also got slightly different numbers when the tests were run a second time. But each time Firefox 5 came out in the lead.