Firefox 3.1 Boosting Javascript Performance
Firefox 3.1 and the respective XULRunner will sport a significant Javascript performance increase through an optimization called tracing by compiling frequently used code paths to native code using a built-in just-in-time (JIT) compiler unit.
Also, I want to highlight a quote by Brendan Eich, inventor of Javascript:
Eich says that Mozilla wants to "get people thinking about JavaScript as a more general-purpose language" and show them that "it really is a platform for writing full applications."
More details in the article
