They get new data, like RSS feeds, Facebook, Twitter, and all that crap. So a lot of widgets have to reload a big portion.
I'm disappointed but that's because of the major updates we got to see in iOS 2, 3, and 4. To me it looks like all there is left to do on iOS is refine everything and throw in a few bells and whistles while we're at it. I can't think of a time I've ever been on iOS since the relase of iOS 5 that there was a feature i thought was really needed and missing. I've just become spoiled lol.
Design is inconsistent as of beta 1. Maps is slow iCloud has privacy problems now with sharing and such.
And I bet he hasn't even tried the developer's preview. You can't say something is fast or slow until you've actually tried it.
I bet it's because it's a beta. iOS 5 beta 1 was buggy as well. Can we get back on topic? WWDC 2012 was disappointing, in my opinion. I never asked to have a iOS vs Android debate regarding how much battery life widgets consume.