Adobe FLEX 2 - CREATING AND EXTENDING COMPONENTS Manual page 199

Using IDeferredInstance in a template component
Deferred creation is a feature of Flex where Flex containers create only the controls that
initially appear to the user. Flex then creates the container's other descendants if the user
navigates to them. For more information, see Chapter 6, "Improving Startup Performance,"
in Building and Deploying Flex 2 Applications.
You can create a template component that also takes advantage of deferred creation. Rather
than having Flex create your component and its properties when the application loads, you
can define a component that only creates its properties when a user navigates to the area of the
application that uses the component. This is especially useful for large components that may
have many child components. Flex view states makes use of this feature.
Implementing a template component 199