It comes with various optimizations for Android 4.0 / 4.1
You might have already had the chance to download and install the latest stable flavor of Firefox for Android, namely version 16.0.1, and you can now have a look at what the newest beta release of the mobile browser has to offer as well.Firefox 17 Beta is now up for grabs on Android, with enhancements for Android 4.0 and 4.1 devices, such as hardware and software decoder support for h.264 video.
Moreover, it brings along Jelly Bean support for Explore by Touch, along with initial web app support.
On top of that, the new release comes with Sandbox attribute for iframes, which should improve the overall security of the app.
Firefox 17 Beta for Android can be downloaded from Softpedia as well, via this link.