Does pack v4 do anything to commits?

Hi Nico,

I had an experiment on speeding up "rev-list --all". If I cache sha-1
of tree and parent, and committer date of single-parent commits, in
binary form, rev-list can be sped up significantly. On linux-2.6.git,
it goes from 14s to 4s (2s to 0.8 for git.git). Profiling shows that
commit parsing (get_sha1_hex, parse_commit_date) dominates rev-list
time.

From what I remember, pack v4 is mainly about changing tree

representation so that we can traverse object DAG as fast as possible.
Do you do anything to commit representation too? Maybe it's worth
storing the above info along with the compressed commit objects in
pack to shave some more seconds.

By the way, is latest packv4 code available somewhere to fetch?
-- 
Duy