Poss a silly question - but are there ways to archive really old messages and generally perform maintenance on my forum from within the control panel or do I need to do something at server mysql level or elsewhere?

A user told me that the site has slowed down a lot recently and I have noticed it a little myself.

Any help much appreciated.

thanks

No way to archive at this time. However, there are a few things to look at.

First one. Since you haven't noticed the slowdown but he has, then it could be related to unread posts if you have full post tracking turned on. If he only visits certain forums, and leaves others unread, then this can contribute. Have him mark all posts as read and see if he notices a difference.

If it's just generally slow for everyone, and this is your own server, or a vps, then you could look at tuning/tweaking your mysql server config. Recommended tool to do this is mysqltuner.pl

Can you run mysqltuner on a shared server to get an idea of what might need to be changed without ticking off the hosting company?

prolly not.. they usually prevent you from peeking too far under the hood

Will it even run?

I'm pretty sure that a root user is required, but I've used it on a "non default" root user so I don't see why it wouldn't run, it just likely won't run "properly" (though it'd likely choke if one of its queries couldn't run)