Profile MSSQL - clear cache and time a query

perf.sql

dbcc freeproccache
go
dbcc dropcleanbuffers
go
DECLARE @a DATETIME, @b DATETIME 
SET @a = CURRENT_TIMESTAMP 
-- QUERY BIT

select * from 
    (select Row_Number() over (order by Id) as RowIndex 
      ,*
  FROM SomeTable) as Sub
    Where Sub.RowIndex >= 1000 and Sub.RowIndex < 2000

-- END QUERY BIT
SET @b = CURRENT_TIMESTAMP 
SELECT DATEDIFF(MS, @a, @b)