Report Takes Long Time Loading

I have a report which is fairly simple but takes a very long time..

It involves the incidents being counted by categories hence it has several Union All.

Also the report numbers are generetd through 2 tables hence within every Union All tehre is a left or an Inner join.

sample code:

SELECT
1 Sort_Order,
COUNT(*) AS Call_Count,
'Incident Resolved at Level 1' AS Count_Type
FROM HOUAPPS237.CallsAndIncidents.dbo.PROBSUMMARYM1 T1
INNER JOIN HOUAPPS237.CallsAndIncidents.dbo.PROBSUMMARYM2 T2
ON T1.NUMBERPRGN = T2.NUMBERPRGN

WHERE PROBLEM_STATUS = 'closed'
AND T2.THIRD_ASSIGNEE IS NULL
AND T2.THIRD_ASSIGNMENT IS NULL
AND T1.SECONDARY_ASSIGNEE IS NULL
AND HAL_FIRST_RES='t'
AND DATEPART(mm, DATEADD(hour, -@offset, CAST(T1.OPEN_TIME AS DATETIME))) = @MONTH
AND DATEPART(yy, DATEADD(hour, -@offset, CAST(T1.OPEN_TIME AS DATETIME))) = @YEAR
AND T1.OTI_ORIGINATOR IN (SELECT Userid FROM HOUAPPS286.HALServiceDesk.dbo.ServiceCenterAgents)

UNION ALL

-- Calls RESOLVED BY L2
SELECT
2 Sort_Order,
COUNT(*) AS Call_Count,
'Incidents Resolved at Level 2 or 3' AS Count_Type
FROM HOUAPPS237.CallsAndIncidents.dbo.PROBSUMMARYM1 T1
LEFT JOIN HOUAPPS237.CallsAndIncidents.dbo.PROBSUMMARYM2 T2
ON T1.NUMBERPRGN = T2.NUMBERPRGN
WHERE (HAL_FIRST_RES<>'t' OR HAL_FIRST_RES IS NULL)
AND PROBLEM_STATUS = 'closed'
AND DATEPART(mm, DATEADD(hour, -@offset, CAST(T1.OPEN_TIME AS DATETIME))) = @MONTH
AND DATEPART(yy, DATEADD(hour, -@offset, CAST(T1.OPEN_TIME AS DATETIME))) = @YEAR
AND T1.OTI_ORIGINATOR IN (SELECT Userid FROM HOUAPPS286.HALServiceDesk.dbo.ServiceCenterAgents)

UNION ALL



could you suggest what might be the reason why teh report churns for so long.

thanks,

kiran.