Mozilla has released a new version of the open source Firefox Web browser. The update brings a much slimmer memory footprint courtesy of Mozilla's MemShrink project. The new release also includes some improvements to hardware-accelerated rendering on Windows, support for the W3C navigation timing specification, and an opt-in system for collecting performance data.

Firefox has historically been a very memory-intensive browser, but Mozilla has pursued several successful campaigns over the years to keep the RAM gluttony in check. One of the most noteworthy memory reduction crusades in Firefox's history took place during the 3.0 development cycle. The impressive result was that Firefox 3.0 scored better than any other mainstream browser at the time in memory-consumption benchmarks. Mozilla has recently renewed its focus on memory reduction with an aggressive optimization project called MemShrink.

According to some statistics published in the Mozilla Hacks blog, the MemShrink effort and other improvements have led to a 20 to 50 percent reduction in overall memory consumption under certain conditions. The improvement is absolutely noticeable during intensive browsing on my old Mac Pro, which has 5GB of RAM. The result is considerably less swapping and modestly better performance under heavy loads.

Although this welcome improvement makes Firefox more pleasant to use, the browser still hasn't quite worked out all of its user interface responsiveness issues yet. I still get lag switching between tabs when I leave the browser running for several days.

One of the challenges that Mozilla faces as it tackles performance issues is that it's hard to track and reproduce performance behaviors that are specific to certain kinds of workloads. To overcome that challenge Mozilla has introduced an intriguing new telemetry framework in version 7 that will monitor performance characteristics and anonymously send data back to the mother ship. The opt-in feature, which can be enabled from the browser's preference dialog, will help Mozilla further improve Firefox performance.

There is a lot to like in the new version, but the add-on ecosystem is still a bit of a mess. Of all the add-ons I use, 1Password is the only one that was fully compatible with Firefox 7 at launch. Fortunately, Mozilla has a plan in place to tackle the add-on compatibility issues for future releases.

The new version of Firefox is available for download from the Mozilla website. For more details about the release, you can refer to the official release announcement.