My wife was complaining about slow logins for our Nextcloud instance. Indeed, while my logins were as fast as expected, her account took over 3 minutes logging in to seeing the Nextcloud Dashboard.

After some internet research I found a thread on the Nextcloud board which recommended checking the auth tokens of the affected user.

That was a good recommendation:

mysql> SELECT uid, count(id) AS nbtokens FROM oc_authtoken GROUP BY uid;
+--------------------------------+----------+
| uid                            | nbtokens |
+--------------------------------+----------+
| m3adows-nextcloud-acc          |       22 |
| my-wifes-nextcloud-acc         |      412 |
+--------------------------------+----------+
5 rows in set (0.00 sec)

Whoops, that’s quite a lot! As the Nextcloud Board user MelwinKfr recommended, I also deleted all her authtokens, as I didn’t care if she had to reconnect her sessions. Beware: This will probably delete all App passwords!

DELETE FROM authtoken WHERE uid = 'my-wifes-nextcloud-acc';
Query OK, 412 rows affected (0.08 sec)

Lo and behold, her login became blazing fast again.

Now, I’m searching for the source of this problem, as it occured multiple times. I suspect it to be Thunderbirds Lightning calendar, but we’ll see about that. I will follow MelwinKfrs advice of using App Passwords for one application after the other to find out which one really was the problematic one.