SQL Query tuning - MS SQL Server -2012 - sql-server

Question

I am new to sql tuning. I have the following SQL which takes around 15 to 20 seconds to produce the results.
SELECT D.DealerName,
Z.Zone,
C.Id ,
L.Id ,
A.Id ,
L.LeadDate,
LT.LeadType ,
EM.FirstName + ' ' + EM.LastName ,
LS.LeadSource ,
--C.*,
E.Id ,
E.StartDateTime,
0 ,
Chiefed = CASE A.AppointmentTypeId
WHEN 3 THEN 'True'
ELSE ''
END,
9 AS WorkflowPhase
FROM Customers C( NOLOCK )
INNER JOIN Dealers D
ON C.DEALERId = D.Id
INNER JOIN Leads L( NOLOCK )
ON L.CustomerId = C.Id
INNER JOIN Appointments A( NOLOCK )
ON A.LeadId = L.Id
AND ( NOT( A.AppointmentTypeId = 5
OR A.AppointmentTypeId = 6 ) )
JOIN CalendarEvents E( NOLOCK )
ON E.TableId = 1
AND E.TableRowId = A.Id
AND E.IsDeleted = 0
AND Dateadd(hh, #TZO, Getdate()) >= E.StartDateTime
LEFT OUTER JOIN AppointmentResults AR( NOLOCK )
ON AR.EventId = E.Id
LEFT OUTER JOIN LeadSources LS( NOLOCK )
ON LS.Id = L.LeadSourceId
LEFT OUTER JOIN LeadTypes LT( NOLOCK )
ON LT.Id = L.LeadTypeId
LEFT OUTER JOIN Users EM( NOLOCK )
ON EM.Id = E.EmployeeId
LEFT OUTER JOIN Zone Z( NOLOCK )
ON Z.Id = C.ZoneId
WHERE EXISTS(SELECT 1
FROM WorkflowStatus WS( NOLOCK )
WHERE TableId = 1
AND TableRowId = A.Id
AND WorkflowPhaseId = 9
AND IsCompleted = 0
AND IsDeleted = 0)
AND ( EXISTS (SELECT 1
FROM dbo.Uft_userpermissionzonesbyworkflow(#EmployeeId, 9)
WHERE ZoneId = C.zoneid) )
AND EXISTS (SELECT 1
FROM Uft_userenableddealers(#EmployeeId)
WHERE DealerId = C.DealerId)
ORDER BY C.LastName,
C.CompanyName,
C.CompanyContact
I already tuned up to my knowledge but still I can see some index scans. I tried to convert those index scans to index seek but it is not possible due to number of records.
Please refer the screenshot of plan diagram and top operations
Kindly provide any suggestions to improvise this query.

Answer 1

DECLARE #p TABLE (DealerId INT PRIMARY KEY WITH (IGNORE_DUP_KEY=ON))
INSERT INTO #p
SELECT DealerId
FROM dbo.Uft_userenableddealers(#EmployeeId)
DECLARE #z TABLE (ZoneId INT PRIMARY KEY WITH (IGNORE_DUP_KEY=ON))
INSERT INTO #z
SELECT ZoneId
FROM dbo.Uft_userpermissionzonesbyworkflow(#EmployeeId, 9)
SELECT ...
FROM ...
WHERE EXISTS(SELECT 1
FROM WorkflowStatus WS( NOLOCK )
WHERE TableId = 1
AND TableRowId = A.Id
AND WorkflowPhaseId = 9
AND IsCompleted = 0
AND IsDeleted = 0)
AND C.zoneid IN (SELECT * FROM #z)
AND C.DealerId IN (SELECT * FROM #p)
ORDER BY C.LastName,
C.CompanyName,
C.CompanyContact
OPTION(RECOMPILE)

Answer 2

as discussed below Devarts answer here the example with a CTE instead of the declared table variables. I'd assume that the declared TVs are faster due to the key, but the CTE is ad-hoc and - maybe - better integrated. Thx for testing:
;WITH p AS
(
SELECT DealerId
FROM dbo.Uft_userenableddealers(#EmployeeId)
)
,z AS
(
SELECT ZoneId
FROM dbo.Uft_userpermissionzonesbyworkflow(#EmployeeId, 9)
)
SELECT ...
FROM ...
WHERE EXISTS(SELECT 1
FROM WorkflowStatus WS( NOLOCK )
WHERE TableId = 1
AND TableRowId = A.Id
AND WorkflowPhaseId = 9
AND IsCompleted = 0
AND IsDeleted = 0)
AND C.zoneid IN (SELECT ZoneId FROM z)
AND C.DealerId IN (SELECT DealerId FROM p)
ORDER BY C.LastName,
C.CompanyName,
C.CompanyContact
OPTION(RECOMPILE)