Costruire Siti Web

My phpbb 3.1. is suffering slowness due to session table. I need someone who can optimized the query SELECT u.*, s.session_time, s.session_viewonline, s.session_start, s.session_page, session_forum_id FROM phpbb_users u LEFT JOIN ( SELECT u.user_id, MAX(s.session_time) as session_time, MIN(s.session_viewonline) AS session_viewonline, session_start, session_page, session_forum_id FROM phpbb_users AS u LEFT JOIN phpbb_sessions AS s ON u.user_id = s.session_user_id WHERE u.user_id = '1' group by u.user_id, session_start, session_page, session_forum_id ) s on u.user_id = s.user_id WHERE u.user_id = '1' ORDER BY session_time DESC\G Please only very professional and expert. Thanks