[Bozos of Bones]

ZFR, you are the first person I know of who is actually annoyed by the tabs. I find them the best intarweb invention ever, most handy they be.
Plus, Firefox will not allow itself to be opened more than once, which means, you can have 51234252 Firefox windows, and they'll all use the memory of just one. The same cannot be said for IE.
So seriously, FF>IE.
And I've never seen FF be any slower, or open less pages than IE. Sure, some morons still design websites with just IE in mind, but for every that kind of moron, you have one kind of idiot who designs pages strictly for Firefox, so it evens out. And as opposed to IE, you can actually train Firefox to open IE-only pages through liberal use of about:config.