Firefox has a reputation for being a memory hog, and the efficiency with which it uses memory has varied over the years. For example, Firefox 2 was quite bad, but Firefox 3, 3.5 and 3.6 were substantially better. But Firefox 4 regressed again, partly due to a large number of new features (not all of which were maximally efficient in their first iteration), and partly due to some over-aggressive tuning of heuristics relating to JavaScript garbage collection and image decoding.
As a result, Mozilla engineers started an effort called MemShrink, the aim of which is to improve Firefox’s speed and stability by reducing its memory usage. A great deal of progress has been made in only 7 weeks, and thanks to Firefox’s new rapid release cycle, each improvement made will make its way into a final release in only 12–18 weeks. (These improvements are available earlier to users on the Aurora and Beta channels.) Firefox 7 is the first release to benefit from MemShrink’s successes, and the benefits are significant.
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Mozilla’s MemShrink efforts are continuing. The endurance test results above show that development versions of Firefox 8 already have even better memory usage, and I expect we’ll continue to make further improvements as time goes on. We also have plans to improve our testing infrastructure which should help prevent future regressions in memory usage.
(não percebo como é que não mexeram nisto há mais tempo).
