[Mark.B]

Ok it seems to be doing this for *every* social group that has a forum:

SELECT
			t.lastpost			
			FROM thread AS t
			WHERE forumid=xxx
			ORDER BY lastpost desc
			LIMIT 1

And also:

SELECT
			SUM(replycount) AS replies,
			COUNT(threadid) AS threads
			FROM thread AS t
			WHERE forumid=xxx
			GROUP BY forumid

So it adds two queries per social group forum.