Optimizing calculation query
You could try applying the filter 

(WHERE concat(SR_PO, '-', SR_RlsSequence) IN ('100063-100', '100063-101', '100063-103', '100063-104'))

Directly on the index instead of it being implemented as a filter further in the execution plan.


You can do this by not applying functions on columns in your where clause and adding an index. The group by is also changed to work without the function. 

Query adaptation:

SELECT 
    concat(SR_PO, '-', SR_RlsSequence) as [Order],
    count(*) as Todo,
    sum(isnull(SR_Enabled,0)) as ToLoad,
    sum(isnull(SR_Done,0)) as Loaded,
    sum(isnull(SR_Enabled,0))-sum(isnull(SR_Done,0))-sum(isnull(Rejected,0)) as Missing,
    count(EndTime3) as Quot,
    sum(isnull(Rejected,0)) as Scrapped
FROM [Edgebanding]
WHERE SR_PO = '100063' AND SR_RlsSequence IN ('100','101','103','104')
GROUP BY SR_PO, SR_RlsSequence;


And index:

CREATE INDEX IX_SR_PO_SR_RlsSequence
ON [dbo].[Edgebanding](SR_PO,SR_RlsSequence)
INCLUDE(SR_Enabled,SR_Done,Rejected,EndTime3);