You got any monitoring stats Dave? Is memory peaking at any point? You say we have capacity, is that server load or RAM?
From the issues we've been having at work, sounds to me like a bit of an inefficient db querieing. Especially if lots of requests are killng it a little. And the issue with the boards on the app.
I've asked a couple of lads from work just now. Very little to go on but I'll see what they say.