just a tip, with iOs 4.3 Apple has updated webkit for safari making it twice as fast as before. I could actually observe it, that's no lie. Now consider this, on iOs 4.2, Firefox "home", just an interface synced with Mozilla server (usually used for the desktop version of FF4) was much faster than Safari. Now it's not just faster, it's a rocket.
Don't get me wrong, due to Apple restrictions, Firefox 4 mobile won't come to the iPhone/iPad/iPod platform, and FF "home" is not a full featured browser. It will sync (from your FF4 desktop) tabs, history and bookmarks (not the passwords), but it's still worth a shot.
http://itunes.apple.com/us/app/firefox-home/id380366933?mt=8