SELECT lpi.defName AS Prozess, SUM(lpi.lCount) AS Schleifendurchläufe FROM
(SELECT inst.definitionname AS defName, inst.instancename AS instName, act.loopcount AS lCount, inst.instanceid AS instId FROM
  (SELECT name AS instancename, id AS instanceid, definitionname FROM view_instance) AS inst
  JOIN
  (SELECT instanceID, name, loopcount FROM view_activity ORDER BY loopcount DESC) AS act ON act.loopcount IS NOT NULL AND act.instanceID = inst.instanceid
  GROUP BY inst.instanceid) AS lpi GROUP BY lpi.defName

SELECT 
defName AS Prozess, 
SUM(lCount) AS Schleifendurchläufe 
 FROM 
  (
    SELECT vi.definitionname AS defName, vi."name" AS instName, va."LOOPCOUNT" AS lCount, vi.id AS piId
    FROM view_instance vi, view_activity va
    WHERE va."LOOPCOUNT" IS NOT NULL 
    AND va."INSTANCEID" = vi.id
  GROUP BY vi.id, vi.definitionname, vi."name",va."LOOPCOUNT") 
  GROUP BY defName​