I'm enjoying the Paizo boards and store... but wonder if you couldn't make it a bit more responsive by paging all the threads and thread lists. As it stands, looking at a board shows all the threads on it, ever, and looking at a thread shows all the posts on it, ever... which must be hitting your infrastructure more than is optimal.
Just a suggestion :)
I also wonder if you wouldn't be better off with fewer tables, and less inline HTML formatting, and more CSS stylesheet goodness. Screw the obsolete browser crowd!