Async Fast Reads/sec is the frequency of reads from Cache pages that bypass the installed file system and retrieve the data directly from the Cache. Normally, file I/O requests will invoke the appropriate file system to retrieve data from a file, but this path permits direct retrieval of Cache data without file system involvement if the data is in the Cache. Even if the data is not in the Cache, one invocation of the file system is avoided. If the data is not in the Cache, the request (application program call) will not wait until the data has been retrieved from disk, but will get control immediately.