Can a Mac user clarify what that is a screenshot of? Most people seem to be a capture of CPU instead of memory use (in which case the author clearly has no idea what he is talking about).

Check out http://www.techdo.com/firefox-wonder-edition/

It's a super slim, zero-install (you can use it side-by side with your current FF installation), modded FF 1.5.

I've been using it for a week and it's a huge relief after putting up with FF2's awful performance for so long! The FF team really needs to fix all their garbage collection flaws in the next version if they want to retain their user base.

I'm seeing less memory usage, so far (I upgraded this afternoon, and have been running for about 8 hours). It also doesn't crash every fifteen minutes the way Gran Paradiso did when I tried it. Firebug 1.1 works, so I'm golden. Got no bookmarks (delicious isn't available yet, I guess), but that won't kill me: I only go to three sites anyway (Google, Reddit, News.YC) and I know those addresses.

After a few minutes of using it my CPU and memory usage spiked. I had to end firefox's process in the end.

More and more I think about switching to a webkit-based browser or opera, although I've never found opera all that great. I really like firefox's UI but it's too much of a resource hog these days.

Memory... what about CPU usage? It too is out of control.

If you are seeing CPU performance degrade with time it is (likely) a symptom of memory fragmentation. I have not seen any rendering benchmarks where gecko fairs significantly worse than the others.

Not sure what the issue is but FF is using about 50% of my CPU.. steady. Other browsers I tried use much, much less (usually less than 5%).

Are you running a dual-core CPU? ;)

It is likely that the pages you view contain aggressive Javascript and Firefox doesn't do enough to tame it.

Yes, c2d. I care only because I hate fans coming on. I like my MBP silent.