PHP Action Deferer: Defer execution of actions until the script ends

This class can defer execution of actions until the script ends.

This way the Web server may close the connection with the user browser before processing intensive actions, making possible for pages to load in less time.

The class can register one or more functions to be called later after the current scripts ends.

It registers a shutdown function that will call all registered deferred action functions.

What is the best PHP page caching class?
Need best caching to store XML documents