I found that turning off addons helps a tremendous amount - on both Windows and Linux. Also, 3.6 appears to be much faster. I don't think Chrome is a safe browser.
It does help, but for me personally FF is pretty worthless without the addons. No firebug? No gestures? What's the difference between it and IE at that point?
What about Chrome, before it added extensions? What about Safari? There are a vast number of ways that other browsers are better than IE, the extensions are just one component of that.
Some of the other browsers definitely have a feature set that's more compelling without extensions. FF really doesn't for me though. The two things I can think of are a slight increase in speed, and the awesomebar (which actually negates some of the speed advantage because it's so slow).
That's definitely nice for me the developer, but it doesn't really matter much for me the consumer. It's a pretty small handful of sites that haven't been wrangled to work in IE. Maybe we'll see more growth in CSS3, Canvas, etc, in use on sites that care less about IE, but for now in practice, that's not much of a difference.
Definitely a valid point, most websites render fine in IE7 and up (though IE6 is losing ground quickly). However, though most people won't examine it beyond their use, easier development generally means better web experiences, so it is in their best interest to use a (more) compliant browser. If nothing else, it's good to encourage more to use FF over IE for that reason.
And personally, I love CSS3 tricks that JavaScript isn't really ideally suited for, and Canvas is a very welcome addition.