Hello,

Directory hashing has a negative impact on some applications (notably
tar and unpatched mutt on large Maildir folders).  For git, it's a win
because hashing destroys locality anyway.

this is inaccurate. Actually turning on directory hashing speeds-up big
maildirs a lot (tested with mutt-1.5.4 and higher with a maildir
containing 30thousand messages). But in the mutt case you also have the
header cache[1] which speeds up a lot - with or without hashed
directories. See also MEs comment[2] on this.

For tar I have no idea why it should slow down the operation, but maybe
you can enlighten us.

	Thomas

[1] http://wwwcip.informatik.uni-erlangen.de/~sithglan/mutt/
	- wait till TLR has released mutt-1.5.10
	- use mutt CVS HEAD
	- use mutt-1.5.9 + http://wwwcip.informatik.uni-erlangen.de/~sithglan/mutt/mutt-cvs-header-cache.29
	- and put the following in your .muttrc:
	set header_cache=/tmp/login-hcache
	set maildir_header_cache_verify=no

[2] http://www.advogato.org/person/scandal/