How to Disable and Free Up Space Used by ReadyBoost on USB Flash Drive

Windows Vista and Windows 7 has built-in a disk caching technology feature named ReadyBoost, which allows a system to boost its performance by adding additional cache memory in the form of Flash memory. When user inserts and plugs in a USB flash drive (or USB key, thumb drive, pendrive, memory key and etc.), user has the option whether to set up and use the USB flash drive as ReadyBoost medium, via AutoPlay dialog box or drive properties.

Windows ReadyBoost will normally take up around 80% of the free space on the USB memory key, which is required to have at least 1 GB of free disk space before ReadyBoost can be activated. The performance improvement and claimed faster speed that brought by ReadyBoost is questionable and not normally noticeable, causing many users choose to disable and turn off ReadyBoost.

When a USB flash drive or thumbdrive is already been set up as ReadyBoost device, Windows 7 or Windows Vista system will automatically reserve and allocated Flash memory space for ReadyBoost system speed by creating a ReadyBoost Cache File named ReadyBoost.sfcache. User who wants to use the USB flash drive to save and store other data can disable or turn off ReadyBoost, and free up the disk space occupied by ReadyBoost.sfcache.

How to Turn Off and Reclaim Disk Space Used by ReadyBoost

  1. Run Windows Explorer.
  2. Right click on the USB flash drive disk icon or drive path and letter that currently running ReadyBoost, and select Properties.
  3. Go to ReadyBoost tab.
  4. Click on radio button for Do not use this device option.
5. Click OK or Apply when done.


  1. You are quite welcome.Thank you for good explanation.Katie Mercado


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