Temp Table Or Nested Select

hi all,
i have speed issue on displaying 4k line of records using temp table.. before this it works fine and fast.. but maybe when i starts joining group by it loads slower.

SELECT DISTINCT customlotno, itemid, ItemName, Ownership, TotalCTNInPlt, TotalCarton, sum(CartonPcs) AS CartonPcs, StorageID, StorageStatus ,OriginUOM, PickQtyUOM, WhsID, WhsName, LocID, Zone, Expirydate, recvDate
INTO #ByItemID
FROM (
SELECT * FROM tblItemdetail
)AS L1
GROUP BY customlotno, itemid, ItemName, ownership, TotalCTNInPlt, TotalCarton, StorageID, StorageStatus ,OriginUOM, PickQtyUOM, WhsID, WhsName, LocID, Zone, Expirydate, recvDate

SELECT *
FROM #ByItemID
ORDER BY CustomLotNo

DROP TABLE #ByItemID

----------------------------
or maybe just use something like nested SELECT like this, but cannot work:-

select customlotno, itemid, locid(

select * from tblitemdetail
where customlotno='IN28606000'

) AS T
GROUP BY customlotno, itemid, locid


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