Hosts having most problems, slow frontend, triggers in problem state

SELECT COUNT(*),
hosts.host,
triggers.description
FROM problem
JOIN triggers ON (triggers.triggerid=problem.objectid)
JOIN functions ON (functions.triggerid=triggers.triggerid)
JOIN items ON (items.itemid=functions.itemid)
JOIN hosts ON (hosts.hostid=items.hostid)
WHERE problem.source=3
AND problem.object=0
GROUP BY functions.functionid,hosts.host,triggers.description
ORDER BY COUNT(*)
DESC LIMIT 15;