Is there any 3rd party utilty available to measure the performance of sqlserver , in an application which is developed by using .NET and MS-SQL Server ?

I wanted to test the applications responce by changing optimising in the stored procedures.

Since it is consuming a lot of resource if the production server is used with a Trace i m thinking of testing the performance by using a test enviornment, but in this case creating the same replica as of a production box is not possible.

can any body sugggest how to create a test application as if 200 users are manipulating the database server ?