### Please describe the problem.

When the assistant starts it takes several hours to do the startup scan, even when there are no files to add.

The repo contains many small files but it is configured to add the smaller ones via gitattributes. In particular there are: 91949 files added to git repo and 1029 annexed.
This is my gitattributes

    * annex.largefiles=(largerthan=500kb)

annex.addunlocked is set to true

### What steps will reproduce the problem?

Create a repo with ~90000 files smaller than 500k and ~1000 files larger (in my case ranging from 500k to 32M). Set addunlocked to true and annex.largefiles to largerthan=500kb. Start the assistant and let it finish adding the files. Restart the assistant.

### What version of git-annex are you using? On what operating system?

git-annex version: 6.20160318
build flags: Assistant Webapp Pairing Testsuite S3(multipartupload)(storageclasses) WebDAV Inotify DBus DesktopNotify XMPP ConcurrentOutput TorrentParser MagicMime Feeds Quvi
key/value backends: SHA256E SHA256 SHA512E SHA512 SHA224E SHA224 SHA384E SHA384 SHA3_256E SHA3_256 SHA3_512E SHA3_512 SHA3_224E SHA3_224 SHA3_384E SHA3_384 SKEIN256E SKEIN256 SKEIN512E SKEIN512 SHA1E SHA1 MD5E MD5 WORM URL
remote types: git gcrypt S3 bup directory rsync web bittorrent webdav tahoe glacier ddar hook external
local repository version: 6

I'm running it on Arch Linux (packaged version)

### Please provide any additional information below.

[[!format sh """

[2016-03-29 22:08:26.356586] main: starting assistant version 6.20160318

  No known network monitor available through dbus; falling back to polling
(scanning...) [2016-03-29 22:08:41.426049] Watcher: Performing startup scan
[2016-03-29 23:05:40.533113] Committer: Committing changes to git
(recording state in git...)
[2016-03-30 00:10:07.085051] Committer: Committing changes to git
(recording state in git...)
[2016-03-30 01:23:29.784236] Committer: Committing changes to git
(recording state in git...)
[2016-03-30 02:43:02.048312] Committer: Committing changes to git
(recording state in git...)
[2016-03-30 03:37:53.273057] Committer: Committing changes to git
(recording state in git...)
[2016-03-30 04:04:56.875573] Committer: Committing changes to git
(recording state in git...)
[2016-03-30 04:31:14.370618] Committer: Committing changes to git
(recording state in git...)
[2016-03-30 04:56:12.467889] Committer: Committing changes to git
(recording state in git...)
[2016-03-30 05:21:09.021728] Committer: Committing changes to git
(recording state in git...)
[2016-03-30 05:43:11.111616] Committer: Committing changes to git
(recording state in git...)
[2016-03-30 06:14:38.096425] Committer: Committing changes to git
(recording state in git...)
[2016-03-30 06:49:54.730879] Committer: Committing changes to git
(recording state in git...)
[2016-03-30 07:26:47.721929] Committer: Committing changes to git
(recording state in git...)


# End of transcript or log.
"""]]

At this point I stopped the assistant that was still doing the startup scan...

### Have you had any luck using git-annex before?

Sure!
