[bad_user]

I am on Firefox 5 and I don't see visible differences between them anymore. Yes, Firefox 3.x used to be visibly slower.

I also don't see visible differences in boot time, but this depends a lot on how many extensions you have -- I only use Firebug and the Web Developer toolbar. And at least Firefox has plugins that aren't totally useless.

[daed]

I think it depends on what hardware you're running. On my laptop Chrome is so noticeably better I only keep Firefox around for testing. On my maxed out desktop I can't tell the difference.

[catshirt]

firefox 4 is visibly slower on a completely fresh install on my mbp. you may have a point about firefox 5, i haven't tried it. my firefox and chrome reference has only been the past to 2 years of major releases.