Both Internet Explorer 7 and Firefox 2 for Windows Vista have been giving me fits for many months with their respective memory leak issues. Firefox 2 has been a bit more stable on my Mac but blows up there now and then too.

I started looking a bit harder at my browsing behavior to try to figure out what causes the problem. IE7 starts out using about 45MB RAM out of the box. However, going to my my.live.com page with about 10 Ajax tabs showed an interesting phenomenon. Every time I moved to a new tab filled with RSS feeds, another couple of megabytes was used up. After moving left to right across the tabs, IE7 was using over 120MB RAM. Clicking a link to open up a new browser tab increased RAM use even more. Closing the tab did not recover memory.

Firefox showed similar memory leakage. And, like IE7 did not recover memory when browser tabs were closed.

Windows Vista seems especially sensitive to this memory leakage. Vista slows down to become nearly unusable (or actually unusable) after a lot (say 160MB) of memory is used by IE7 or Firefox. And, this is on a PC with 2GB total RAM.

This doesn't seem to happen on a Mac running OS X Leopard. Firefox does crash more than it should there though.