Sql IN clause slows down performance

Question

I need a help about sql query performance...

I have a view and when I run view as

select * 
from udv_salesAnalyze 
where _month=12 and _year=2012 

I got result in 2 seconds

but when I add another filter as

select * from udv_salesAnalyze 
where _month=12 and _year=2012 
and userRef in (1,2,5,6,9,11,12,13,14
,19,22,25,26,27,31,34,35,37,38,39,41,47,48,49,53,54,57,59,61,62
,65,66,67,68,69,70,74,77,78,79,80,83,86,87,88,90,91,92,94)  

I got result in 1 min 38 seconds..

I modified query as

select * from udv_salesAnalyze 
where _month=12 and _year=2012 
and userRef in (select * from udf_dependedUsers(2)) 

(here udf_dependedUsers is table returned Function) I got result in 38 seconds

I joined table retuned function to view but again I got result in 38-40 seconds...

is there any other way to get result more fastly...

I ll be very appreciated you can give me a solution...

thanks a lot ...

here code fo udf_dependedUsers :

ALTER FUNCTION [dbo].[udfn_dependedUsers] (@userId int)
RETURNS @dependedUsers table (userRef int)
AS
BEGIN
DECLARE @ID INT
SET @ID = @userId
;WITH ret AS(SELECT userId FROM users
             WHERE  userId = @ID
             UNION ALL
             SELECT t.userId
             FROM   users t INNER JOIN ret r ON t.Manager = r.userId
             ) 
insert into @dependedUsers (userRef)
select * from ret
order by userId
RETURN 
END

Answer 1

Try using a left join

select * from udv_salasAnalyze  MainTable
LEFT JOIN
(select * from udf_dependedUsers(2)) SelectiveInTable --Try direct query like that you wrote in user function
ON SelectiveInTable.userRef = MainTable.userRef
where _month=12 and _year=2012 
and SelectiveInTable.userRef != null