Thanks for the detailed reply.

I am running both the quries at the same time and also doing DBCC DROPCLEANBUFFER and DBCC CLEARPROCCACHE before for both the queries.

If this is a table or index scan howz the execution cost of 2nd query is less than the first one. Ultimately a table or index scan is costlier than an index seek on this table as it has some millions of rows. I have checked the query plan and there was no index or table scan on this table. I will try and post the plan.

Is there a way to check the number of bytes of data that is being fetched by a sproc per execution if not a query?