The AFS Cache file is stored by default at %TEMP%\AFSCache in a persistent file marked with the Hidden and System attributes.  The persistent nature of the data stored in the cache file improves the performance of OpenAFS by reducing the number of times data must be read from the AFS file servers. 

The performance of the AFS Client Service is significantly affected by the access times associated with the AFSCache paging file.   When given the choice, the AFSCache file should be placed on a fast disk, preferably NTFS, the file should not be compressed and should consist of as few fragments as possible.   Significant performance gains can be achieved by defragmenting the AFSCache file with SysInternal's Contig utility while the AFS Client Service is stopped.