Optimise thread load query

Thanks, @torohill

include/class.thread.php

@@ -39,18 +39,14 @@ class Thread {
 
         $sql='SELECT ticket.ticket_id as id '
             .' ,count(DISTINCT attach.attach_id) as attachments '
-            .' ,count(DISTINCT message.id) as messages '
-            .' ,count(DISTINCT response.id) as responses '
-            .' ,count(DISTINCT note.id) as notes '
+            ." ,count(DISTINCT CASE WHEN thread.thread_type = 'M' THEN thread.id ELSE NULL END) as messages "
+            ." ,count(DISTINCT CASE WHEN thread.thread_type = 'R' THEN thread.id ELSE NULL END) as responses "
+            ." ,count(DISTINCT CASE WHEN thread.thread_type = 'N' THEN thread.id ELSE NULL END) as notes "
             .' FROM '.TICKET_TABLE.' ticket '
             .' LEFT JOIN '.TICKET_ATTACHMENT_TABLE.' attach ON ('
                 .'ticket.ticket_id=attach.ticket_id) '
-            .' LEFT JOIN '.TICKET_THREAD_TABLE.' message ON ('
-                ."ticket.ticket_id=message.ticket_id AND message.thread_type = 'M') "
-            .' LEFT JOIN '.TICKET_THREAD_TABLE.' response ON ('
-                ."ticket.ticket_id=response.ticket_id AND response.thread_type = 'R') "
-            .' LEFT JOIN '.TICKET_THREAD_TABLE.' note ON ( '
-                ."ticket.ticket_id=note.ticket_id AND note.thread_type = 'N') "
+            .' LEFT JOIN '.TICKET_THREAD_TABLE.' thread ON ('
+                .'ticket.ticket_id=thread.ticket_id) '
             .' WHERE ticket.ticket_id='.db_input($this->getTicketId())
             .' GROUP BY ticket.ticket_id';