Optimize query with sql server - sql

Question

I have the following query .its execution took 15 min .It is too much slowly .
Is there a way to optimize it ?
Query
SELECT
Id,Fees,WeekOfMonth,CONVERT(NVARCHAR(MAX), StartDate, 103) AS StartDate,CONVERT(NVARCHAR(MAX), EndDate, 103) AS EndDate,'Temp Fees ' AS FeesName
,#MonthName AS [MonthName]
INTO ##TempFeesMonthly
from
(
SELECT DISTINCT
1 as Id,sum(((CNTI_THPAYE *(CNTI_THFACT / CNTI_THPAYE)) *
(CASE WHEN CNTI_DURHEBDO IS NULL THEN 1 ELSE CNTI_DURHEBDO/5 END)*#NumberOfDays)) AS Fees,WeekOfMonth,StartDate,EndDate
FROM SCHHAYS.dbo.WTVTAT TAT
LEFT JOIN
SCHHAYS.dbo.WTTIEINT INT
ON (
TAT.TIE_ID = INT.TIE_ID
)
AND (
TAT.VTAT_IORDRE = INT.TIEI_ORDRE
)
LEFT JOIN
SCHHAYS.dbo.PYCONTRAT CC
ON TAT.PER_ID = CC.PER_ID
AND TAT.CNT_ID = CC.CNT_ID
LEFT JOIN
SCHHAYS.dbo.CMTIERS T
ON TAT.TIE_ID = T.TIE_ID
LEFT JOIN
SCHHAYS.dbo.WTMISS M
ON CC.PER_ID = M.PER_ID
AND CC.CNT_ID = M.CNT_ID
LEFT JOIN
##WTCNTIWeek COT1
ON M.PER_ID = COT1.PER_ID
AND M.CNT_ID = COT1.CNT_ID
INNER JOIN
SCHHAYS.dbo.WTPRH AS PRH
ON M.PER_ID = PRH.PER_ID
AND M.CNT_ID = PRH.CNT_ID
AND M.TIE_ID = PRH.TIE_ID
INNER JOIN
##tempStartEndWeekDates AS Tsed
ON PRH_DTEDEBSEM>=Tsed.StartDate
AND PRH_DTEFINSEM<=Tsed.EndDate
LEFT JOIN
SCHHAYS.dbo.WTSCCT C
ON CC.RGPCNT_ID = C.RGPCNT_ID
AND CC.PER_ID = C.PER_ID
AND CC.CNT_ID = C.CNT_ID
INNER JOIN
##TempHaysStaffWeek HF
ON C.VAPO_CODE = HF.onetouch COLLATE Latin1_General_CI_AS
group by
WeekOfMonth,StartDate,EndDate)t
--CREATE INDEX IDX_TempFeesMonthly ON ##TempFeesMonthly(WeekOfMonth)
--Calcul Temp Margin
UNION ALL
--INSERT INTO ##TempFeesMonthly(Id,Fees,WeekOfMonth,StartDate,EndDate,FeesName,[MonthName])
SELECT
2, sum(Fees) AS Fees ,WeekOfMonth,CONVERT(NVARCHAR(MAX), StartDate, 103) AS StartDate,CONVERT(NVARCHAR(MAX), EndDate, 103) AS EndDate,'Temp Margin ' AS FeesName
,#MonthName AS [MonthName]
from
(
SELECT DISTINCT
sum((CASE WHEN CNTI_DURHEBDO IS NULL THEN 1 ELSE CNTI_DURHEBDO/5 END)*#NumberOfDays)-(CNTI_THPAYE *(CASE WHEN CNTI_DURHEBDO IS NULL THEN 1 ELSE CNTI_DURHEBDO/5 END)*1.453*1.21*#NumberOfDays) AS Fees,WeekOfMonth,StartDate,EndDate
FROM SCHHAYS.dbo.WTVTAT TAT
LEFT JOIN
SCHHAYS.dbo.WTTIEINT INT
ON (
TAT.TIE_ID = INT.TIE_ID
)
AND (
TAT.VTAT_IORDRE = INT.TIEI_ORDRE
)
LEFT JOIN
SCHHAYS.dbo.PYCONTRAT CC
ON TAT.PER_ID = CC.PER_ID
AND TAT.CNT_ID = CC.CNT_ID
LEFT JOIN
SCHHAYS.dbo.CMTIERS T
ON TAT.TIE_ID = T.TIE_ID
LEFT JOIN
SCHHAYS.dbo.WTMISS M
ON CC.PER_ID = M.PER_ID
AND CC.CNT_ID = M.CNT_ID
LEFT JOIN
##WTCNTIWeek COT1
ON M.PER_ID = COT1.PER_ID
AND M.CNT_ID = COT1.CNT_ID
INNER JOIN
SCHHAYS.dbo.WTPRH AS PRH
ON M.PER_ID = PRH.PER_ID
AND M.CNT_ID = PRH.CNT_ID
AND M.TIE_ID = PRH.TIE_ID
INNER JOIN
##tempStartEndWeekDates AS Tsed
ON PRH_DTEDEBSEM>=Tsed.StartDate
AND PRH_DTEFINSEM<=Tsed.EndDate
LEFT JOIN
SCHHAYS.dbo.WTSCCT C
ON CC.RGPCNT_ID = C.RGPCNT_ID
AND CC.PER_ID = C.PER_ID
AND CC.CNT_ID = C.CNT_ID
INNER JOIN
##TempHaysStaffWeek HF
ON C.VAPO_CODE = HF.onetouch COLLATE Latin1_General_CI_AS
group by
WeekOfMonth,StartDate,EndDate,CNTI_THPAYE,CNTI_DURHEBDO)t
GROUP BY WeekOfMonth,StartDate,EndDate