Weird, my 3GS seems no different on iOS 5 vs iOS 4. At worst, it's nothing like the iOS 4 performance on the iPhone 3G. This video apparently shows the 3GS being faster than iPhone 4 (believable, actually, if you consider the quadrupling of pixels on the iPhone 4 from the 3GS): http://techuncover.com/blog/tag/iphone-3gs-is-faster-on-ios-...

It's entirely possible that ios's shitty performance is due to me rescuing it from brick state via oven, but I don't really buy it. The phone works perfectly, except that it's very slow and experiences the occasional hang. It's. Ertainly nowhere near as smooth as my buddy's 4s. I don't expect it to be, but I do expect it to unlock without a 4 second lag.