When the first benchmarks with the Internet Explorer 8.0 Beta 1 came out, I was curious to see how much better IE would be compared to it's predecessor.
If you look at Apple's established SunSipder JavaScript benchmark, you will find that IE 8 is about 4.5 times faster than IE 7. First of all, this is great news for all web developers, But if you look carefully, you will notice that IE 8 benefits most from the results in the string section.

IE always had performance problems with string operations. Even when Microsoft's developers promised to solve this problem, it existed all the time — until now. That is the reason why superior JavaScript frameworks have an option to replace all used strings with variables to avoid this browser weakness. ;-)
Anyway — I am very happy to see, that this huge issue is finally fixed.

If you run the SunSpider benchmark without the string tests, the final result looks different: the increase of performance reduces to 1.5. Do not get me wrong, I do not want to put down IE team's effort: they have done a fantastic work; not only in performance but also in standards support and they have included an excellent debugger. I just want to straighten out that most of the gain in performance comes "for free", as it derives from a bugfix for a quite old issue.

While today's support for web standards is pretty well, web applications are spreading like wild fire and web applications for mobile devices are getting more important, web browsers vendors are working hard on optimizing their products for speed and memory footprint.
This results in the fact that nightly builds of Webkit and Firefox are 3 to 6 times faster than IE 8. These are (and will be!) the products Internet Explorer is compared with.

There are interesting times ahead and I am looking forward to see the results in the final version of the browsers. :-)