woman-cache-filename

woman-cache-filename is a variable defined in `woman.el'.
Its value is

nil

Documentation:
The full pathname of the WoMan directory and topic cache file.
It is used to save and restore the cache between sessions. This is
especially useful with remote-mounted man page files! The default
value of nil suppresses this action. The `standard' non-nil
filename is "~/.wmncach.el". Remember that a prefix argument forces
the `woman' command to update and re-write the cache.

You can customize this variable.