I've been taking backups for the forum for the last year and only just noticed that our database size is stable at around 550-600mb. Sometimes it is 589mb, next backup will be 560mb in size.
I would have thought that on a very busy forum, this should be going in one direction in that it gets bigger. We are aware of some threads that have disappeared for some reason but we put that down to a moderator maybe deleting them by accident.
It's a strange one, just wondering if this sounds right to people - that the database isn't really growing in size and indeed sometimes losing 10% of its volume.