Quoting bwilson(a)clickshift.com, from the post of Wed, 08 Sep:
Using subdirectory trees fixes an ancient UNIX problem that happens when
there are several hundred of files in one directory -- if this is allowed
to happen the system will sllloooooowwwww ddooooooowwwwwnnnn
every time the full directory is accessed.
yo! don't generalize! my ReiserFS deals quite fine with tens of
thousands of files in a directories, and probably more :-)
--
Apocalipse horseman
Ira Abramov
http://ira.abramov.org/email/