I've noticed since upgrading to Firefox 3 that my browser (and general system) performance has been much better. An independent consultant claims that it's now the most efficient browser on the market in regard to memory leaks, at least for Windows, and Safari has problems (though it's not clear whether that's just on Windows, or on Macs as well).
I frequently use a bunch of different tabs(sometimes more than 20), and in FF2, that would usually cause FF2 to use about a gigabyte of memory. When those tabs were closed, FF2 would still use about .8 gigs until it was shut down.
FF3 uses less than .2 gigs in the same basic situation. My relatively new computer is back to being a high performance machine with the addition of FF3.
I have one page open - yours - and Firefox 3 is taking up 114 Meg. It started at 40 Meg a couple of hours ago, never had more than 2 tabs open and usually only one. Seems pretty ridiculous to me. To think we went to the moon on less RAM than is in my Caller ID box, and now I need Multivac to run a page browser.
On my work computer I run a little systray app called FreeRamXP Pro and it lets me keep an eye on my system's available RAM in a free state. This current station only has 512 meg and with FF2 I was always bouncing against the page file. Now with FF3 I have about 120 free and also have a couple of other apps open as well.
Using Process Explorer I can see that FF3 is using about 90 megs with 8 tabs open at the moment. This same situation on FF2 would have likely resulted in a working set of about 200 megs by now.