Are there technical reasons why Android is not as smooth as iOS and can they be overcome? There are some discussions of this topic on the internet but I'm looking for something objective and technical like the Stack Exchange community is generally quite good at.

I've resisted the smartphone and tablet wave thus far but will probably buy my first Android device soon and start developing for the platform.

I much prefer Android's openness to Apple's walled garden. But the thing that bothers me most is that iOS is silky smooth and Android is not, even on pretty powerful devices with multiple CPU and graphics cores.

Is this something that's already overcome in newer Android or that is really on a problem on older/cheaper devices? Or is it inherent due to Android being fully multitasking and based on Unix?

Edit
(In response to the possibility that this question invites opinion based answers) :

This question is not intended to be opinion based but rather to gather information on real differences in software or hardware that are responsible for the large differences in test results of factors such as Touch screen responsiveness, and rendering speed of UI elements of the Android and iOS operating systems.

Expected answer:


Answer that pinpoints exact differences in software implementations and reasons for doing so that have lead to disparities in responsiveness
Differences in specific hardware (such as the touch screen) that can be a cause
All backed up with actual test results if possible
Any other relevant and well defined causes/reasons
There is an article that discusses the semi-technical reasons/issues that have lead to the differences in smoothness of Android and iPhone devices. 

But after gathering some key points from the article one can conclude:


From the very start, IOS had been built around a  multi-touch screen (meaning IOS had been built from the gound up to be very responsive as opposed to most other OSs that adopted full screen multi-touch displays)
Yes, it is not always hardware (processing power) dependent it is merely a result of IOS operating system giving more priority to UI rendering, etc where as Android distributes the processing power equaly (this may be an advantage or drawback as with a faster UI everything from download speeds to loading content will slow down)


  
  UI rendering occurs on the main thread of an app
  UI rendering has normal priority
  

Android is very popularly known to be highly customization and it is simply a matter of tweaking kernel parameters like 'lowmemkiller' that can make UI:


  amazingly smooth -- easily as smooth as the iPhone or WP7 phones

It is not that Android lacks the potential, but simply that developers prefer to spend resources elsewhere (like on the  bigger screens of some devices). Then why doesn't Android spend more resources on UI? 


Well, Android is widely distributed among a wide variety of devices, and that is exactly why when it comes to android, only individual owners can overcome these (there is no optimum setting Android developers can set... every device that runs Android has its own set of 'optimum settings' and every user has his own perspective on what they should be 'optimum settings'). So the solution, balance the power...
And no it is not something that has been 'overcome' on newer Android devices. But it depends on what you mean by overcome, as the lowmemkiller of rooted android devices can easily be tweaked (but it comes as a cost to battery,etc...)



For more technicality, see Dianne Hackborn and Andrew Munn