A method and apparatus delivers a file from a content provider to a requesting client. A request from a client to access a file is received, a common file that is common to all requesting clients is identified in a first storage location, in a second storage location a personalized file that is unique to said client is identified, the common file and are personalized file are analyzed to find their differences, the shared data and the unique data are delivered to the client and the client is instructed to stitch the shared data and the unique data together.