While testing to Moodle.org 2.8 upgrade, the course overview block had to be disabled because of this query. On the live site its quicker because our mysql server is better tuned/hardware etc, but its still crazy.

Query_time: 280.587464 Lock_time: 0.000243 Rows_sent: 54 Rows_examined: 1005350

SELECT d.forum,d.course,COUNT(p.id) AS count FROM forum_posts p JOIN forum_discussions d ON p.discussion = d.id LEFT JOIN forum_read r ON r.postid = p.id AND r.userid = '168461' WHERE ((d.forum = '15' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '32' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '24' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '485' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '94' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1048' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1162' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '934' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '117' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '125' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '466' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1006' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '118' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '119' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '587' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1197' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '141' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1156' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1001' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '999' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '116' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1023' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '126' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '337' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '120' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '333' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1189' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '469' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '121' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '122' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1000' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '365' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '123' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '366' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '124' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '27' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '25' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '128' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1164' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '396' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1157' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '30' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '512' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '397' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1058' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1007' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '130' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1115' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '967' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '352' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '941' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '224' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '29' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1114' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '965' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '33' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1161' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '34' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1190' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '26' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1159' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '998' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1153' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '340' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '905' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '806' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '170' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '925' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '342' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '959' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1200' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1168' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1160' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1154' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1128' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1082' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '1016' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '981' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '896' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) OR (d.forum = '777' AND (d.groupid = -1 OR d.groupid = 0 OR d.groupid = '0')) ) AND p.modified >= '1412938490' AND r.id is NULL GROUP BY d.forum,d.course;