The way in which Mozilla Firefox has used memory has changed over the years, improving from one version to another. Firefox 3, 3.5 and 3.6 were considerable enhancement over Firefox 2. But when Mozilla released Firefox 4, it kind of regressed, instead of improving, mainly due to a large number of new features and to Java script. As to overcome the shortcomings, Mozilla aimed to improve Firefox’s speed and stability by reducing memory usage and released MemShrink. Soon, step by step progresses have been made and Firefox 7 is the first to benefit from MemShrink’s success. Memory usage significantly depends on how the browser acts. Still, there is no specific way to determine or measure the memory usage, with only several different metrics that could be used in order to estimate it. Of course, the more tabs are open, the less enjoyable the browsing experience is.
In order to measure Firefox 7 memory usage, some endurance tests on Firefox 6, 7 and 8 were performed using the MozMill add-on. By repeatedly opening and closing pages from 100 widely used websites in 30 tabs, memory usage was tracked in detail. A graphic showed the average and peak resident memory usage for each browser, after five such tests. The measurements varied from one test to another, but all in all, the endurance test shows the following reductions in memory usage:
Minimum resident: 1.1% — 23.5% (median 6.6%) Maximum resident: -3.5% — 17.9% (median 9.6%) Average resident: 4.4% — 27.3% (median 20.0%)
Another test of comparison between Firefox 5 and Firefox 7 has been undertaken by Nathan Kirsch from Legit Reviews. He opened 117 bookmarks, each one in a separate tab, by clicking “Open all in Tabs” on a bookmark folder. After loading, he measured the “private working set” by using Windows Task Manager. The result? Firefox 7 used half a GB less memory than Firefox 5, meaning a 39.7% reduction. The tests may not be the exact indicator of memory usage, but all in all, Firefox 7 uses less memory than previous versions and it is both leaner and faster. And the improvements are less likely to stop here.
