Not True Anymore

"Most browser benchmarks are isolated, artificial tests that can be gamed by browser vendors optimizing those specific cases. With only those benchmarks to go on, the folks at LucidChart were skeptical that the IE9 beta would actually outperform other modern browsers in real-world applications. To separate hype from reality, they built their first browser benchmarking tool,
http://www.lucidchart.com/blog/2010/09/16/ie9-ff4-beta-in-real-world-benchmark/
 based in LucidChart itself. This benchmark is to SunSpider what a Left4Dead 2 benchmark is to 3Dmark Vantage. Product specs don't matter, only real-world performance on a real-world application. The results were surprising. IE9 held its own pretty well (with a few caveats), and the latest Firefox 4 beta came in dead last."