Codeigniter - >> Abnormal load on the database server

Hello everyone, help me figure it out ..

Hoster complained "Abnormal load on the database server" to a large load in the code:

function searchTutor($param1 = '', $param2 = '', $param3 = '') { //echo "Under Construction";die(); $this->data['search_data'] = array(); $query_tail = " GROUP BY u.id ORDER BY u.is_premium = 1"; $condition_location = " AND 1=1 "; $condition_subject = " AND 1=1 "; $condition_experience = " AND 1=1 "; $condition_tutor_type = " AND 1=1 "; /** * * Common Query * with all condition predefined * */ $query = " SELECT u.*, ts.subject_id, s.subject_name, l.location_name, (SELECT pl.location_name FROM ".$this->db->dbprefix( 'locations' )." pl WHERE pl.id = l.parent_location_id ) AS parent_location_name, tt.tutor_type FROM dt_users u, dt_tutor_subjects ts, dt_tutor_locations tl, dt_subjects s, dt_locations l, dt_tutor_types tt, dt_tutor_selected_types tst, dt_users_groups ug WHERE ug.group_id = 3 AND u.active = 1 AND ts.subject_id = s.id AND u.location_id = l.id AND u.id = ug.user_id AND tt.tutor_type_id = tst.tutor_type_id "; 

Maybe somewhere to remove or add something? Give advice where to dig .. Thanks in advance!