ReadyBoost is Windows Vista feature that allows the user to plug a USB flash memory device into a USB 2.0 port on the PC and use it as a cache or virtual memory.  The advantage being that it is much faster to cache to the USB drive than caching to your hard disk, speeding up your system and enhancing overall performance.  Acting as a fast store for frequently accessed data, the average random 4K read from a flash device is about ten times faster than accessing the same information from the hard drive.

Select Use this device.  Here you can also set how much space ReadyBoost should reserve for the cache - the most space you reserve, the faster things go. That’s all there is to it!  ReadyBoost is working.  You can conform this by looking at the contents of the drive through Windows Explorer.  If it’s working you’ll see the ReadyBoost file (which as the .sfcache extension).

There are two ways that you can disable ReadyBoost.  First, you can just disconnect the drive from the system.  This won’t cause any system instabilities or data loss because the flash drive is not used as an exclusive data store, only as a high-speed cache, so the only thing you’ll notice if you remove the drive is a drop in  performance.  (The only drawback to this is that the ReadyBoost cache file will remain on the drive and take up storage space until you deleted it manually.)

The best way to disable ReadyBoost is to shut it down properly.

• Fire up Windows Explorer and find the drive
• Right click and select Properties
• Click on the ReadyBoost tab
• Select Do not use this device.
• Click OK.

This deletes the cache file for you, once again freeing up space on your flash drive.