Steve tackles this issue in an editorial over at All About Symbian.
I can’t help but notice that you’re comparing a 3 GHz x86 chip with a 200 MHz OMAP processor. Apples to oranges doesn’t even come close to describing that comparison. I acknowledge the fact that there are many things occurring at once in the OS, but it still doesn’t mean I should have to wait for the screen to reflect the action I inputed on the keypad. Processes aren’t being prioritized correctly.
I hope you attend the "Evening with S60" event in London so you can try a S60v3FP2 device for yourself. It’s honestly just as fast as S40, if not faster. I wish I could’ve tested it with the transitions turned off, but honestly I wouldn’t even bother disabling them. They’re so subtle that Mikko had to point them out to some people.
He was running FP2 on a Nokia 6290, it has a 348 MHz Freescale processor. Did that have anything to do with it? Probably.
I’ll wait until Nokia sends you a FP2 device to review to see what you have to say the about perceived performance. It certainly was one of the first things I noticed.