The Windows prefetch folder is a specific location within the Windows operating system (OS) that contains a series of small files detailing the startup activities and frequently-used application programs.
Each time the computer starts, the prefetcher portion of the memory manager in Windows references the prefetch folder to learn about previous startup activities and the applications that were used. By caching the details of previous successful startups in the prefetch folder, Windows can accelerate subsequent startups and improve startup performance.
Prefetching is beneficial to the Windows operating system because a typical Windows startup involves a multitude of files that often must be opened multiple times. This multiple-access behavior can take considerable time and slow the boot-up process.
Prefetching traces the system startup activity and creates a record of just what instructions and data are accessed. Future startups can use that trace data to load the instructions and data far more efficiently and speeding the effective system startup.
The prefetch folder is typically stored within the Windows System folder (\Windows\Prefetch) and trace files always include a .PF extension (for “PreFetch”). The prefetch folder will contain at least one boot trace file called NTOSBOOT-B00DFAAD.PF along with additional trace files for each application. The prefetch files for applications are generally amalgams of the application name and a hash code. For example, the prefetch file for Adobe Acrobat Reader may be named ACRORD32.EXE-1CE22EA3.PF.
Windows maintains the prefetch folder automatically, and no direct intervention is required from IT administrators or individual computer users. It is generally not recommended to empty the prefetch folder manually. This will not damage the OS, but it will force Windows to re-create the prefetch files for the operating system and applications -- actually slowing the system's apparent performance until the .PF files are recreated.