[mbelshe]

The great thing and the worst thing about benchmarks is that vendors optimize to them :-)

IE9 claims speed, but the only benchmark it performs better than other browsers on is the SunSpider benchmark. If it is so fast, why does it only do well on a single benchmark? It has already been documented that trivial changes to SS make IE9's performance change dramatically: http://blog.mozilla.com/rob-sayre/2010/11/16/reporting-a-bug...

Personally, I believe SunSpider is just too-easy-to-game. Historically, this problem comes up now and then with compiler vendors and benchmarks. The only solution is to have long-running benchmarks which exercise many parts of the JS engine so that gaming is not so easy.

[kenjackson]

Actually the IE9 SS issue was a bug. It's since been fixed and no longer displays this weird behavior in IE9.

IE9 also does well on other benchmarks too like the Facebook graphics benchmark, where I think the only browser to beat it was FF4.

[mbelshe]

There were multiple issues. There was a straight up bug, which was fixed. But the perf delta remains.

[mbelshe]

You can see this for yourself - run the test referenced in Rob's post above. IE9, right now, reports a 13-14x slowdown on that test with trivial changes.

[kenjackson]

I don't believe so. I had checked this and the perf issue went away. Maybe you're referring to a different issue. Can you post a link with perf data?