I'm not sure what to say to this. I'm almost convinced you've spent almost no considerable time with a Galaxy Nexus. I've seen the iphone 4, ipad 1 and especially the 3GS stutter and choke on numerous occasions depending on how data intensive a task was. They're all still fairly smooth running, but no where near the kind of flawless performance found on a 4S or iPad 2.
You're going to have to explain better where this "noticeably more smooth" is demonstrated for me to see where you're coming from. I mean, you have to take into consideration just how different any given part of the OS is between the two platforms. Home screens on an Android phone can be filled with data intensive widgets and live wallpapers. On ios, you have static app icons. One device is also rendering at a MUCH higher resolution than any of its competitor's devices.
Maybe I should do a video that shows all the core stock apps running on both platforms, and scroll up and down furiously to demonstrate the parity between them. I'm just not buying this noticeably more smooth business. Not at all.
*We ARE talking stock OS and apps here right? If you bring in 3rd party apps, then yeah, no contest. The iphones shit all over android ICS or otherwise.