Simplify SQL where exists in clause - sql-server

Question

I want to simplify the below given procedure especially I want to remove most of the where clause filters such as IN and exists clauses.
For that, I have used a CTE and also declare a temp table and used it to get the select query that was talking long time since it was in where in clause. I would appreciate if you could show me some tricks in order to simplify this query.
ALTER PROCEDURE dbo.GetMappingBranchScenarios
#Mapping INT
#UserId INT= NULL
#BranchId INT = NULL
SELECT
BS.BranchId,
NULLIF( CC.Code, '' ) AS Code,
BS.BranchName,
BS.Active
FROM
Branch BS
LEFT OUTER JOIN
Code CC ON CC.BranchId = BS.BranchId
LEFT OUTER JOIN
BranchRule BRE ON BRE.MappingId = #Mapping
AND BRE.BranchId = BS.BranchId
WHERE
(BS.Active = 1
OR EXISTS (SELECT * FROM BranchRule BRE
WHERE BRE.BranchId = BS.BranchId
AND BRE.BranchId > 0
AND BRE.MappingId = #MappingId))
AND (#UserId IS NULL
OR BS.BranchId IN (SELECT BranchId
FROM branch2mapping.dbo.ListBranch(#UserId))
OR EXISTS (SELECT 1 FROM dbo.SecondaryMapping
WHERE Id = #UserId AND Admin = 1))
AND BS.BranchId = (CASE WHEN BranchId is NULL THEN BS.BranchID ELSE #BranchId END)
AND CC.Code = (CASE WHEN #Code IS NULL THEN CC.Code ELSE #Code END)
ORDER BY
CC.Code ASC
What I have done so far :
IF OBJECT_ID('tempdb..#Temp', 'U') IS NOT NULL
DROP TABLE #Temp
CREATE TABLE #Temp (BranchId INT)
SELECT BranchId
FROM branch2mapping.dbo.ListBranch(#UserId)
;WITH CTE AS
(
SELECT
BS.BranchId,
NULLIF(CC.Code, '' ) AS Code,
BS.BranchName, BS.Active
FROM
Branch BS
LEFT OUTER JOIN
Code CC ON CC.BranchId = BS.BranchId
LEFT OUTER JOIN
BranchRule BRE ON BRE.MappingId = #Mapping
AND BRE.BranchId = BS.BranchId
)
SELECT *
FROM CTE
WHERE
(CTE.Active = 1
OR EXISTS (SELECT * FROM BranchRule BRE
WHERE BRE.BranchId = CTE.BranchId
AND BRE.BranchId > 0
AND BRE.MappingId = #MappingId))
AND (#UserId IS NULL
OR BS.BranchId IN (SELECT * FROM #Temp)
OR EXISTS (SELECT 1 FROM dbo.SecondaryMapping
WHERE Id = #UserId AND Admin = 1)
)
AND BS.BranchId = (CASE WHEN BranchId is NULL THEN CTE.BranchID ELSE #BranchId END)
AND CTE.Code = (CASE WHEN #Code IS NULL THEN CTE.Code ELSE #Code END)
ORDER BY
CTE.Code ASC
Thank you for all your help.

Answer 1

Could you try if this is faster and still returning the same values with different filtering criteria?
ALTER PROCEDURE dbo.GetMappingBranchScenarios
#Mapping INT
#UserId INT= NULL
#BranchId INT = NULL
DECLARE #IsRuleExists BIT;
DECLARE #IsUrerADmin BIT;
IF EXISTS
(
SELECT 1
FROM Branch BS
INNER JOIN BranchRule BRE
ON BRE.BranchId = BS.BranchId
AND BRE.BranchId > 0
AND BRE.MappingId = #MappingId
)
BEGIN;
SET #IsRuleExists = 1;
END;
IF EXISTS
(
SELECT 1
FROM dbo.SecondaryMapping
WHERE Id = #UserId AND Admin = 1
) OR #UserId IS NULL
BEGIN;
SET #IsUrerADmin = 1;
END;
CREATE TABLE #Branches
(
[BranchId] INT
);
INSERT INTO #Branches ([BranchId])
SELECT BranchId
FROM branch2mapping.dbo.ListBranch(#UserId);
SELECT
BS.BranchId,
NULLIF( CC.Code, '' ) AS Code,
BS.BranchName,
BS.Active
FROM Branch BS
LEFT OUTER JOIN Code CC
ON CC.BranchId = BS.BranchId
WHERE
(
BS.Active = 1 OR #IsRuleExists = 1
)
AND
(
#IsUrerADmin = 1
OR
BS.BranchId IN (SELECT BranchId FROM #Branches)
)
AND BS.BranchId = (CASE WHEN BranchId is NULL THEN BS.BranchID ELSE #BranchId END)
AND CC.Code = (CASE WHEN #Code IS NULL THEN CC.Code ELSE #Code END)
ORDER BY CC.Code ASC;