In their official stable versions, IE9 and Chrome used the most memory in the 15-tab scenario. (Expect that number increase drastically if you're the type who switches between 40 or more tabs.) Firefox 10, however, beat them all: It consumed around half (!) of the memory that the others needed in this scenario. Although its basic resource usage ran at 68 MB, it scaled quite well up to 218 MB when loading five tabs.

How does this translate to real-world performance? Both IE9 and Chrome felt sluggish, with noticeable delays in switching between tabs. Also, overall system performance and responsiveness degraded. Firefox had no discernible effect on performance whatsoever.

Now let's move on to the beta releases of Opera, Firefox, and Chrome.

Firefox's beta did not achieve a significant improvement over the production version when opening one or or five tabs, tough it did shave another 70 MB off on the 15-tab test. Google Chrome, too, improved things a tad when only a handful of tabs were running, but it failed miserably with a usage of 1,084 MB at just 15 tabs -- unnacceptable! The beta version of Opera had a difficulty with one of our websites as its memory increased to 789 MB at five tabs. At 15 tabs, over 1,112 MB of memory was consumed, which shows that the beta version needs to go a long, long way to match the memory consumption of version 10. All browsers, with the exception of Firefox, showed visible lags -- it was no fun surfing the web or trying to work with other programs.