Marco Costalba [off-list ref] writes:
What I use now is:
git-diff-tree -r --name-status sha1 sha2
An then I parse the output for 'A' or 'D' as first char of
each line. When I found one of that two chars I kwnow trees
have different files set.
The problem is that if sha1 and sha2 correspond to very
"distant" revision the output of git-diff-tree can be very
long and also usless as long as I stop searching at first
match.
Perhaps
$ git-diff-tree -r --name-status --diff-filter=AD sha1 sha2
would help you somewhat? This would not make the diff
generation part quicker, but at least you do not have to parse
other types of changes.