Mozilla tested Firefox 3.0 Beta 4, Firefox 2.0 and Internet Explorer 7 in terms of memory usage and the conclusion favors the last iteration of the open source browser over its predecessor, but also over the proprietary Microsoft product. The Redmond company, following the release of IE7, acknowledged the existence of problems related to memory leaks and with websites remaining opened for large periods of time in the browser. The scenario is illustrative of the high memory usage issues that have plagued Internet Explorer 7.

In this context, it shouldn't come as a surprise that Mozilla, after testing the memory usage of Firefox 2.0, IE7 and Firefox 3.0 Beta 4, has come to the conclusion that the latest development milestone for version 3.0 of its open source browser delivers superior memory handling capabilities compared to its alternatives. In a test performed by Stuart Parmenter, a Software Engineer working at Mozilla Corporation, the memory usage of Firefox 3.0 Beta 4 is stabilized under 100 MB, while Internet Explorer 7 uses five times as much approaching 500 MB.

"All browsers increase in memory use slightly over time, but the Firefox 3 slope is closer to 0. The _peak_ of Firefox 3 is lower than the terminal size of Firefox 2! The terminal state of Firefox 3 is nearly 140MB smaller than Firefox 2. 60% less memory! IE7 doesn't appear to give any memory back, even after all the windows are closed! Firefox 3 ends up about 400mb smaller than IE7 at the end of the test," stated Parmenter.

And performance is one of the areas where Microsoft acknowledged the fact that IE7 is inferior to Firefox 3.0. During the keynote address delivered at MIX08 in the first week of March by Dean Hachamovitch, General Manager Internet Explorer, a graphic comparing IE7, IE8 Beta 1, Firefox 3.0 Beta 3 and Safari 3 Beta, clearly showed that Internet Explorer 7 was lagging in terms of performance behind rival browsers. However, while Mozilla said nothing about IE8, Hachamovitch stated that the performances were almost the same as Firefox 3.0 Beta 3. But as far as IE7 is concerned, there is no comparison with Firefox 3.0 Beta 3.

"Our work has paid off. We're significantly smaller than previous versions of Firefox and other browsers. You can keep the browser open for much longer using much less memory. Extensions are much less likely to cause leaks. We've got automated tools in place to detect leaks that might result from new code. We're always monitoring and testing to make sure we're moving in the right direction. All of this has been done while dramatically improving performance."