Generally, over a period of time, you tend to abuse the root class. In my current project I see that we tend to "use" many modules, in the root class, that are not neccessary in most of the places, thereby increasing the memory.

  Although you could create a single root class (like Objective-C's NSObject), try to have specialized root classes (maybe a root class for all your UI's and one for your model classes) which would inherit from your single root class.