AppleInsider | IE8’s JavaScript performance lags well behind Safari, Chrome
Above is a recent article on the JavaScript performance of the next-generation web browsers/rendering engines, including IE8, Firefox 3.1, Webkit r40220, Chrome 2.0.158.0 and Opera 10.
From the test result in the article, we can see that the performance of JS varies a lot across the browsers (up to 1:10). This make developing cross-platform web apps using AJAX much more difficult since you need to make it as lightweight as possible.
Developing in Flash would not face this problem because swf content runs inside the virtual machine. Although it has been claimed that Flash content runs relatively slower under Mac, but the different is not noticeable in most cases. And the performance of ActionScript (3) is A LOT higher than JavaScript in any browser.
When developing large scale CPU hungry web apps, you better use Flash instead of AJAX. (for other stuff, AJAX may be better, or a lot better…)
PS. I’ve googled around for some benchmarks on AS/JS to prove my point, but seems that there is no recent benchmark that aims for this (only a 2007 one). Hopefully I will have time to do it by myself in this week.