Android needs more core in order to provide the same user experience as dual core system running in WP8. This is a fact and even acknowledged by the android team themselves and they don't intend to change this in near future.
Although the GUI is not as smooth as IOS or WP8, it should performs up on par with others when running application.
The sluggishness of android is due to it doesn't provides as much cpu cycle as others to process the touch and GUI.