Ok, that means I don't have to check out git-lfs, git-fat or git-bigstore. My annex is 250k symlinks pointing to 250 GiB of data. It's slow enough as it is.
At 250k files in one branch, you are starting to run into other scalability limits in git too, like the innefficient method it uses to update .git/index (rewriting the whole thing).
There is the new "split-index" mode to avoid this (see "git update-index" man page). The base index will contains 250k files but .git/index only contains entries you update, should be a lot fewer than 250k files.
It seems that `--split-index` is only available at 'update-index'. Can it be used with `add` or via `git config`?