We should offer a manner of monitoring the performance of Mjolnir

[Yoric]

I have the suspicion that is_user_banned and is_room_banned can be quite slow if too many users show up in the list. We should find a way to monitor this.

[grahamc]

This sounds useful to me, it takes 3-5 minutes for my bot to apply a ban.

[turt2live]

+1 to grafana metrics in general