[[!comment format=mdwn
 username="joey"
 subject="""comment 3"""
 date="2016-05-31T16:02:01Z"
 content="""
copy --to has to query the git-annex branch to see if the file is on the remote.
So it has worse locality than copy --from, which can simply stat the local
file to see if it's present.

Whatever inneficiencies git-annex has here are well swamped by the overhead
of git querying the branch. 

When the remote has most of the files already, `git annex copy --to remote` is
similar to `git annex find --not --in remote`.

Here I've ran that under /usr/bin/time, and it looks like git-annex
ran for 89 seconds out of the 260 second runtime. So at least 65% of the total
runtime is spent by git querying the branch.

	89.26user 6.92system 4:20.80elapsed 36%CPU (0avgtext+0avgdata 75584maxresident)k
	516432inputs+0outputs (0major+31156minor)pagefaults 0swaps
"""]]