Don't know about other versions, but I get more crappy page rendering and shitty Java/Plug-in support on the Mac version of IE than it's version of Mozilla.
On the Mac like the PC, IE might be a bit snapier but I find Mozilla's overall performance to be supperior. Viewing even the pages Zombie484879546542 sayd Mozilla fucked up, seemed to render fine.
Foruthermore, I don't know what you guys are talking about when you say Opera on a PC is not faster, it's got it's problems but speed is certainly not one of them.
As far as IE loading part of it's code in to memory, that goes back to M$'s bullshit privetized API's which is unfair buisness in the first place. It dosn't matter what the competition does or want's to do, because M$ reserves a hefty chunk of it's fastest code for themselves.
Anyway, the best browser ever made is Netscape Communicator 4.5, and I wish they woulden't have switched to that shitty Netscape 6. If they kept developing the 4.5 core they would have had the best browser for sure.