SuperFetch is a performance enhancement introduced in Microsoft Windows Vista to reduce the time necessary to launch applications. An expansion from the Prefetch files found in Windows XP, they record usage scenarios and load resources into memory before they are needed.
Data from SuperFetch is gathered by the sysmain.dll, part of svchost.exe, and stored in a series of files in the %SystemRoot%\Prefetch directory. These files appear to start with the prefix Ag and have a .db extension. The format of these files is not known, but they are not actually databases.
The SuperFetch feature is seeded with some basic usage patterns when the operating system is installed .