When did this all begin? I am reminded that you say you're on shared hosting. So were your forums performing just fine for a long while and then all of a sudden this happened? Or was this performance change some related to a script change or increase in server load based on a modified/added script by you or someone else on the same server?
As a random thought, does those happen when you create a new topic, or only when you reply to a topic?
Is your forum email settings configured correctly? How many email notifications are being sent out for your post reply?
Do you get the same page lag when you "Email This Post To Me" ?
