SqlCommand Parameters Best Practices

I was writing a simple sign up class the other day and coded
a Register method with a SqlCommand and Parameters like this:



            SqlCommand sqlCmd =
new SqlCommand("Regester", sqlConn);

            sqlCmd.CommandType =
CommandType.StoredProcedure;

           

           
sqlCmd.Parameters.Add("@UserName", SqlDbType.VarChar, 55);

           
sqlCmd.Parameters["@UserName"].Value = userName;



           
sqlCmd.Parameters.Add("@Firstname", SqlDbType.VarChar, 55);

           
sqlCmd.Parameters["@Firstname"].Value = fName;



             etc...



Seems pretty straight forward right? A senior coder writes his params like this



            SqlParameter pUserName
= new SqlParameter("@UserName", SqlDbType.VarChar, 55);

            pUserName .Value =
address2;

           
sqlCmd.Parameters.Add(pUserName );



            SqlParameter pFName =
new SqlParameter("@FName", SqlDbType.VarChar, 55);

            pFName .Value = city;

           
sqlCmd.Parameters.Add(pFName );



            etc...



What is the benefit, if any, of creating a new instance of SqlParameter for
each value passed to the sp?



How could I easily test the code for speed and resource use besides tracing?