There's no particularly important reason to uncompress these things,  
so this issue could be solved by removing the --uncompress option  
from darcs optimize.

I am uncompressing these things in order to pack a complete repo  
tighter:

column 1: tar the whole repo, 2: tar and gzip -9 the whole repo,  
column 3: 7z the whole repo
row A: standard darcs-2 format, row B: run "gunzip -r" on it first to  
uncompress any gzipped files

		1		2		3
A		40 M	32 M	27 M
B		83 M	32 M	18 M

size of resulting tarball

Regards,

Zooko