.SFCACHE File Extension
File TypeReadyBoost Cache File
File format categories include Binary, Text, XML, and Zip. The format of this file type has not been determined.
What is an SFCACHE file?
Cache file used by Windows Vista and 7 that may be created on a flash memory device; adds additional memory that Windows may access as virtual RAM, which may help improve system performance.
ReadyBoost can be enabled by right-clicking the icon of a flash memory device and selecting "Properties." Then click the ReadyBoost tab and check "Use this device." This will create a temporary file named "ReadyBoost.sfcache" on the flash disk.