Firefox  14 just arrived but Firefox 15 is already in Beta and will be released before you know it. So what exactly does Firefox 15 bring us? Well it is too early to provide a full official changelog but there are a few interesting changes you can expect.
Without a doubt one of the major end-user affecting improvements made in Firefox 15 is the plugging of memory leaks (i.e. excess RAM usage) by addons. Mozilla has put great effort into fixing Firefox’s memory leaking issues but addon memory leakage has still been a thorn in Mozilla’s side. According to Nicholas Nethercote, a Mozilla programmer, Firefox 15 has successfully implemented a fix for memory leaking addons:
We have confirmed, via in-house testing and from real-world telemetry data, that it [Firefox 15] prevents the vast majority of leaks that occur in existing add-ons.
Users who upgrade to Firefox 15 won’t have to upgrade their add-ons to see the benefits. While it is hard to predict the effect of this improvement on any individual user, many users should experience greatly reduced memory consumption, particularly on long browsing sessions. This should result in better performance, fewer pauses, and fewer crashes.
How exactly did Mozilla fix addon memory leaks and why did it take so long? There is a huge blog post by Nicholas  providing answers which you can read yourself if you are interested. I, personally, am just happy this fix has been implemented.
Other changes made to Firefox 15 so far are:
- Support for the new audio format, Opus. According to Mozilla, “Opus is a completely free audio format that was recently approved for publication as a standards-track RFC by the IETF” and “Opus offers these benefits: Better compression than MP3, Ogg, or AAC formats; good for both music and speech; dynamically adjustable bitrate, audio bandwidth, and coding delay; and support for both interactive and pre-recorded applications”.
- A new “Responsive Web Design” view which can be used to easily resize pages
- A new “Layout View” in the Style Inspector tool
- Page Inspector highlighting behavior can now be triggered on/off
- Web Console has been improved, making it faster
[via Mozilla ]