Тяжелые запросы к базе

SELECT c.id as id,
                       c.target as target,
                       c.target_id as target_id,
                       c.target_link as target_link, 
                       c.content as content,
                       c.guestname,
                       c.pubdate as fpubdate,
                       IFNULL(c.user_id, 0) as user_id,
                       IFNULL(u.nickname, '') as author,
                       IFNULL(u.login, '') as author_login,
                       IFNULL(v.total_rating, 0) as rating
				FROM hs_users u, hs_comments c
                LEFT JOIN hs_ratings_total v ON v.item_id=c.id AND v.target='comment'
				WHERE (c.user_id=u.id OR c.guestname<>'') AND c.published=1  AND (c.target="article" OR c.target="blog" OR c.target="palbum" OR c.target="photo" OR c.target="userphoto" OR c.target="catalog" OR c.target="faq")
                GROUP BY c.id
                ORDER BY c.pubdate DESC
                LIMIT 100;