Performance is not only about raw speed. Your application will be perceived as being fast as long as it appears fast to the user, and to appear fast your application must be responsive. As an example, to appear faster, your application can defer allocations until objects are needed, a technique known as lazy initialization, and during the development process you most likely want to detect when slow code is executed in performance-sensitive calls.
The following classes are the cornerstones of most Android Java applications:
Fragment(Android 3.0 and above)
Of particular interest in these classes are all the
onSomething() methods that are called from the main thread, ...