If you're a Firefox fan that just has to be on the cutting edge, you'll be pleased to hear that the Mozilla Foundation has released the first public beta for Firefox 3.1.

According to Download.com the main change for 3.1 above the current Firefox 3.0 release is a different JavaScript engine with vastly improved performance, alongside a smartened user interface for switching between tabs, and improvements to the so-called 'Awesome Bar'.

The new JavaScript engine, the most important change over existing Firefox builds, is included in the beta but deactivated by default. In order to make use of the improved engine – codenamed TraceMonkey – you'll have to make a tweak in Firefox's internal configurations via the about:config menu accessible from the location bar. By changing the value of javascript.options.jit.content to true, the new TraceMonkey engine will be enabled the next time you start Firefox.

When the fiddling is over and done with, you should be rewarded with a marked improvement to JavaScript rendering performance. According to tests performed by Download.com on the SunSpider benchmark suite, Firefox 3.1 Beta 1 completed the tests in 2787.6 milliseconds compared to Firefox 3.0.3 – which doesn't use the TraceMonkey engine – achieving a rather poorer 5446.6 milliseconds. Although the SunSpider tests are an extreme case, the figures still demonstrate that a noticeable improvement is possible on JavaScript-heavy sites.

As if this wasn't enough, the beta also features an in-built version of the Geode location-tracking system, which was previously only available as a limited-functionality plugin. Coupled with the aforementioned improved tab switching UI – using CTRL+Tab to move between tabs brings up a snazzy Vista-style graphical interface – and you've got yourself a pretty decent browser to be playing with.

It's not all plain sailing, however: the private browsing functionality that almost every browser seems to be offering these days hasn't made it into this first beta, and many plugins designed for Firefox 3.0 are incompatible with Firefox 3.1. Despite this, if you're after possibly the fastest browser currently available then it's definitely worth playing with: download your copy from the Mozilla website.

Are you hoping that Firefox 3.1 will offer more than simple performance improvements, or have the likes of Opera and Safari – and even Google's Chrome – already tempted you away from the incandescent vulpine? Share your thoughts over in the forums.