[Bug-tar] High per file overhead?

[Phillip Susi]

Can anyone explain this?

~$: du -bsh Maildir/
98M     Maildir/
~$: tar cf Maildir.tar Maildir/
~$: du -bsh Maildir.tar
112M    Maildir.tar
~$: find Maildir | cpio -o -H newc > Maildir.cpio
204433 blocks
~$: du -bsh Maildir.cpio
100M    Maildir.cpio

Why does tar have 12M more overhead than cpio?  This Maildir is the lkml 
since Jan 1, so it contains ~20,000 messages/files, but ~734 bytes per 
file seems like a bit much for overhead.