The current nightly build of Firefox has made a bit of noise around the internet in certain circles due to the new optimisation techniques Mozilla are using to greatly increase the performance of JavaScript. Previously, performance concerns have often been mentioned with regards to Firefox, but now it looks like at least once performance issue will no longer be a problem in Firefox 3.1 when it is released.
Ars Technica has posted a number of graphs indicating the performance differences between "Tracemonkey" and Firefox 3 when using various JavaScript. One example of the improvement is for function calls. If Firefox 3 was benchmarked at 1.0, then Tracemonkey is 26 times faster. I'd say that's pretty impressive, but when you look at the performance increase for global loops it's even better!
