Compound File Optimization
Asynchronous storage enables applications to precisely layout compound files so that data is available in the order in which applications will require it. If an application requires only part of its data to display a first page of information, this data can be placed at the beginning of the file, even if it logically resides at the end of a stream. Data from different streams can be interleaved. Audio and video data, for example, can be interleaved so that subsequent read operations retrieve both simultaneously, a requirement for multimedia applications.
IStorage::CopyTo can be used to layout a docfile, thus improving performance in most scenarios.