Firefox Enables Generational GC To Compete With Chrome
Written by Michael Larabel in Mozilla on 30 March 2014 at 12:45 PM EDT. 26 Comments
The latest Mozilla Firefox nightly builds have begun enabling the generational garbage collector to better compete with Google's Chrome on performance grounds.

Going back to late 2010 there have been patches that implement generational garbage collection for JavaScript within Mozilla's browser. A Generational GC model is known to enhance the memory performance for many garbage collectors, including the GC employed by Google's Chrome browser for JavaScript. There's been much written about implementing a generational garbage collector within this Wiki page and this bug report.

What's new to share today is that the Generational GC is now enabled by default in the latest Firefox nightly builds. The change was finally accepted to turn on the "GGC" for desktop versions of Firefox.

Unfortunately, the Generational GC isn't fully polished yet. Some users are reporting big increases of memory use for Firefox with the new collector. One OS X user reported the start-up memory use being up by 14MB (8%), with 50 tabs open the memory use is up by 117MB or 9%, and after closing the 50 tabs the memory use was up by 35MB or 8%. See the aforelinked bug report for more details. With follow-up testing, however, the results appeared to be more positive.

Look for the Generational GC by default in future versions of Firefox (v31) and stay tuned for more information and testing.

About The Author
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Michael Larabel is the principal author of and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and automated benchmarking software. He can be followed via Twitter or contacted via

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