I'm working in v7 mode with `annex.largefiles` configured.  When I add a lot of files (1000 in the example below), it takes 2 mins for the `(recording state in git...)` phase to complete.  The same happens if I just add files directly using `git add`.  Running `git add -v` will slowly list the files, so it's apparent that the adding of the files to git is what's causing the delay.  Is this slow `add` performance normal when adding files to git through git-annex?

I didn't want to report this as a *bug* since I don't know if this is the result of a known process that git-annex is performing.  However, I find it curious how adding the same files to git-annex directly (without `annex.largefiles` configured) is very fast.

If this is not a bug, perhaps the `(recording state in git...)` output could show the files being added instead to avoid the suspicion that the `add` command is hanging.

I'm using git-annex version 7.20190912-gab739242a3 (with git version 2.23.0).

Here is an example I've been using to investigate the different conditions and the output from a run of the script:

```
#!/usr/bin/env bash

set -eu

dir=$(mktemp -d)
cd ${dir}

cleanup() {
    chmod 777 -R ${dir}
    rm -rf ${dir}
}

trap cleanup EXIT

# create 1000 files
for idx in {1..1000}; do
    echo ${RANDOM} > file${idx}
done

git init
set -x

time git add . > /dev/null
git rm --cached -r . > /dev/null

git annex init

time git annex add -c annex.largefiles="largerthan=1M" .
git rm --cached -r . > /dev/null

time git add .
```


```
Initialized empty Git repository in /tmp/tmp.BdmH199gbk/.git/
+ git add .
real    0m0.049s
user    0m0.010s
sys 0m0.039s
+ git rm --cached -r .
+ git annex init
init  (scanning for unlocked files...)
ok
(recording state in git...)
+ git annex add -c annex.largefiles=largerthan=1M .
real    2m4.617s
user    1m40.865s
sys     0m18.335s
+ git rm --cached -r .
+ git add .
real    2m13.367s
user    1m48.507s
sys     0m21.230s
+ cleanup
+ chmod 777 -R /tmp/tmp.BdmH199gbk
+ rm -rf /tmp/tmp.BdmH199gbk
```
