The amount of information that WoMan caches (in main memory and,
optionally, saved to disc) is controlled by the user option
woman-cache-level. There is a trade-off between the speed with
which WoMan can find a file and the size of the cache, and the default
setting gives a reasonable compromise.
The woman command always performs a certain amount of caching in
main memory, but it can also write its cache to the filestore as a
persistent cache under control of the user option
woman-cache-filename. If persistent caching is turned on then
WoMan re-loads its internal cache from the cache file almost
instantaneously, so that there is never any perceptible start-up delay
except when WoMan rebuilds its cache. Persistent caching is
currently turned off by default. This is because users with persistent
caching turned on may overlook the need to force WoMan to rebuild its
cache the first time they run it after they have installed new man
files; with persistent caching turned off, WoMan automatically rebuilds
its cache every time it is run in a new Emacs session.
A prefix argument always causes the woman command (only) to
rebuild its topic cache, and to re-save it to
woman-cache-filename if this variable has a non-nil value. This
is necessary if the names of any of the directories or files in
the paths specified by woman-manpath or woman-path change.
If WoMan user options that affect the cache are changed then WoMan will
automatically update its cache file on disc (if one is in use) the next
time it is run in a new Emacs session.