Windows: What's Prefetcher, SuperFetch, ReadyBoost?

By Xah Lee. Date:

I learned about Windows's Prefetcher and SuperFetch. Basically, Prefetcher is a tech that fills your memory in anticipation of use for the purpose of making your computer faster. SuperFetch is a improved version of Prefetch. Quote from Wikipedia:

The Prefetcher is a component of versions of Microsoft Windows starting with Windows XP.[1] It is a component of the Memory Manager that speeds up the Windows boot process, and shortens the amount of time it takes to start up programs. In Windows Vista, SuperFetch and ReadyBoost [2] extend upon the prefetcher and attempt to accelerate application and boot launch times respectively by monitoring and adapting to usage patterns over periods of time and loading the majority of the files and data needed by them into memory so that they can be accessed very quickly when needed.

SuperFetch is a technology that pre-loads commonly used applications into memory to reduce their load times. It is based on the "prefetcher" function in Windows XP.[9]


ReadyBoost is a similar tech to SuperFetch. If you have any flash drive connected, it'll try to use it as a cache to speed things up, because harddisk is much slower.

ReadyBoost is a disk cache component of Microsoft Windows, first introduced with Microsoft's Windows Vista in 2006 and bundled with Windows 7 in 2009. It works by using flash memory, a USB flash drive, SD card, CompactFlash or any kind of portable flash mass storage system as a cache.

For some detail in using ReadyBoost, see: Windows: is Your USB Drive Fast Enough for ReadyBoost? .