filesets-cache-save-often-flag

filesets-cache-save-often-flag is a variable defined in `filesets.el'.
Its value is

nil

Documentation:
Non-nil means save buffer on every change of the filesets menu.
If this variable is set to nil and if Emacs crashes, the cache and
filesets-data could get out of sync. Set this to t if this happens from
time to time or if the fileset cache causes troubles.

You can customize this variable.