Regarding:

This status path code is here to speedup addall, which currently is excessively slow due to adding every single unignored file to the index even if it has no changes. Remove this when it's fixed in libgit2 libgit2/libgit2#2687

(https://github.com/nodegit/nodegit/blob/master/lib/index.js#L27)

The issue seems to be resolved via:

libgit2/libgit2#3109