Time Difference Sotored Proc &> Job &> Seperate Query

I have seen in this forum that many people has posted like my query time taken problem. But I couldn't get clear solution for this.

Here is the my issue:-
I have written couple of batch query to bring data from another sql server.
I have used proper index and index hints for these query.
I have used SET NOCOUNT ON in stored procedure.

I am having the time difference for one of the blow qeury in various running process that executed in QA as single query , stored procedure for whole batch query and schedule this stored procedure in job

sotored Proc = 31 second > job =28 second > seperate query = 12 second.


one of 15 batch query

declare @last smalldatetime
set @last ='11/08/2002'

UPDATE ENTERPRISE_STATE
SET RESP_BUYER_FST_NAME = i.first_name,
RESP_BUYER_LST_NAME = i.last_name
FROM oesd.dbo.individual i WITH (NOLOCK index(XPKindividual))
INNER JOIN Leap.dbo.fnIndBuyer(@last) fn
ON fn.individual_num=i.individual_num
WHERE ENTERPRISE_NUM = fn.enterprise_num



Anbody can able to give proper reason why I am getting this time difference.

Thabnks,
Ravi