Firefox 3 goes on a diet, eats less memory than IE and Opera
Benchmarks show that Firefox 3 uses less memory than Internet Explorer 7 and Opera. A number of significant fixes and improvements have brought down the open-source browser’s memory footprint and could make it a more viable choice in mobile environments.
http://arstechnica.com/news.ars/post/20080317-firefox-3-goes-on-a-diet-eats-less-memory-than-ie-and-opera.html