Command Timeout, longer to get response back - c#-4.0

Question

I am executing large query,so my app throwing time out error. Some of the thread suggested to added command time out but after adding those lines it take longer to get response back, any idea why or what am i missing in my code?
public int CreateRecord(string theCommand, DataSet theInputData)
{
int functionReturnValue = 0;
int retVal = 0;
SqlParameter objSqlParameter = default(SqlParameter);
DataSet dsParameter = new DataSet();
int i = 0;
try
{
//Set the command text (stored procedure name or SQL statement).
mobj_SqlCommand.CommandTimeout = 120;
mobj_SqlCommand.CommandText = theCommand;
mobj_SqlCommand.CommandType = CommandType.StoredProcedure;
for (i = 0; i <= (theInputData.Tables.Count - 1); i++)
{
if (theInputData.Tables[i].Rows.Count > 0)
{
dsParameter.Tables.Add(theInputData.Tables[i].Copy());
}
}
objSqlParameter = new SqlParameter("#theXmlData", SqlDbType.Text);
objSqlParameter.Direction = ParameterDirection.Input;
objSqlParameter.Value = "<?xml version=\"1.0\" encoding=\"iso-8859-1\"?>" + dsParameter.GetXml();
//Attach to the parameter to mobj_SqlCommand.
mobj_SqlCommand.Parameters.Add(objSqlParameter);
//Finally, execute the command.
retVal = (int)mobj_SqlCommand.ExecuteScalar();
//Detach the parameters from mobj_SqlCommand, so it can be used again.
mobj_SqlCommand.Parameters.Clear();
functionReturnValue = retVal;
}
catch (Exception ex)
{
throw new System.Exception(ex.Message);
}
finally
{
//Clean up the objects created in this object.
if (mobj_SqlConnection.State == ConnectionState.Open)
{
mobj_SqlConnection.Close();
mobj_SqlConnection.Dispose();
mobj_SqlConnection = null;
}
if ((mobj_SqlCommand != null))
{
mobj_SqlCommand.Dispose();
mobj_SqlCommand = null;
}
if ((mobj_SqlDataAdapter != null))
{
mobj_SqlDataAdapter.Dispose();
mobj_SqlDataAdapter = null;
}
if ((dsParameter != null))
{
dsParameter.Dispose();
dsParameter = null;
}
objSqlParameter = null;
}
return functionReturnValue;
}