Speeding up SQL query(s) - sql

Question

New to SQL Server so I am sorry if this is not correctly. We have a number of stored procedures. The one shown below is a good example.
The issue with the query is it works fine until there are thousands of records and it sometimes never returns. I am told this could be performance related and that queries like this could be improved by using local variables. Any insight would be appreciated...thanks
CREATE PROCEDURE [dbo].[Status_GetObjectConfigurationsPr]
#SiteID int,
#AnalogBinary bit,
#UserID int,
#ActionNumber int
AS
DECLARE #ProcName varchar(128),
#ErrorText varchar(200),
#ErrorID int,
#RoleID int
SELECT #RoleID = RoleID
FROM TESUserRole
WHERE UserID = #UserID
SELECT #ProcName = OBJECT_NAME(##PROCID)
SELECT
o.ObjectID,
o.ObjectName,
o.ObjectType,
o.ObjectURI,
o.KeyName,
c.UserDefinedUnits,
o.SiteID,
ts.SiteName,
p.Device_ID,
c.Dimension,
CASE
(SELECT COUNT(ParentObjectID) FROM TESObjectParent
WHERE ChildObjectID IN (o.ObjectID))
WHEN 2
THEN (SELECT TOP 1 b.ParentObjectID
FROM TESObject a
INNER JOIN TESObjectParent b ON a.ObjectID = b.ParentObjectID
WHERE a.ObjectID IN (SELECT ParentObjectID
FROM TESObjectParent
WHERE ChildObjectID IN (o.ObjectID))
AND ObjectType != 8
AND RelationshipType = 7)
WHEN 1
THEN (SELECT TOP 1 ParentObjectID
FROM TESObjectParent
WHERE ChildObjectID = o.ObjectID AND RelationshipType = 7)
END AS ParentObjectId,
CASE
(Select count(ParentObjectID) from TESObjectParent where ChildObjectID in (o.ObjectID) )
When 2 Then ((select top 1 ObjectName from TESObject a inner join TESObjectParent b
on a.ObjectID = b.ParentObjectID where a.ObjectID in
(Select ParentObjectID from TESObjectParent where ChildObjectID in (o.ObjectID))
and ObjectType != 8 and RelationshipType = 7))
When 1 Then PanelName
End
as PanelName
FROM
TESObject o
LEFT OUTER JOIN
TESObjectConfiguration c
ON
o.ObjectID = c.ObjectID
INNER JOIN
TESSite ts
ON
o.SiteID =ts.SiteID
INNER JOIN
TESPanel p
ON
o.Device_ID = p.Device_ID and o.SiteID = p.SiteID
INNER JOIN
TESObjectFamily f
ON
o.CustomFamilyNumber = f.FamilyNumber
INNER JOIN
TESEquipmentRole er
ON
er.FamilyID = f.FamilyID AND er.ObjectType = o.ObjectType
INNER JOIN
TESAction a
ON
er.ActionID = a.ActionID
WHERE
p.IsAppliedToLicense = 1 AND p.IsPanelEnabled = 1
AND
o.SiteID = #SiteID
AND
(c.Property_ID = 85 OR c.Property_ID is NULL)
AND(
(#AnalogBinary = 0 AND o.ObjectType IN (4,5))
OR
(#AnalogBinary = 1 AND o.ObjectType IN (1,2))
)
AND
er.RoleID = #RoleID
AND
a.ActionNumber = #ActionNumber
SET #ErrorID = ##ERROR
IF #ErrorID <> 0
BEGIN
SET #ErrorText = 'Unable to retrieve Object Configuration Information.'
GOTO ErrorHandler
END
---- Error Handling
RETURN 0
ErrorHandler:
BEGIN
RAISERROR ('PROC: %s - %s , Error: %d.', 16, 1, #ProcName, #ErrorText, #ErrorID)
END
RETURN 1