You might want to take a look at this video (Flash challenged here). Seems some relatively common tasks slow down dramatically. Would speed hits plus relatively few enhancements in iOS 4 for 3G owners cause any of you to hang back on 3.1.3?…if you haven’t updated already? via DF
Update: We’re hearing in the comments that people are seeing same speed on their 4.0 builds as the faster build in the video. Weird.