public void TimingLambdaExpressionVsCallback() {

      _lambdaStopwatch.Start();

      var lambdaQuery = _mgr.Employees;

      lambdaQuery.ExecuteAsync(e => {

        var employees1 = new ObservableCollection<Employee>();

        e.Results.ForEach(employees1.Add);

        _lambdaStopwatch.Stop();

        Output += "_lambdaStopwatch = " + _lambdaStopwatch.ElapsedMilliseconds + Environment.NewLine;

      });

      _callbackStopwatch.Start();

      var callbackQuery = _mgr.Employees.ExecuteAsync();

      callbackQuery.Completed += callbackQuery_Completed;

    }

    void callbackQuery_Completed(object sender, EntityQueriedEventArgs<Employee> e) {

      var employees2 = new ObservableCollection<Employee>();

      e.Results.ForEach(employees2.Add);

      _callbackStopwatch.Stop();

      Output += "_callbackStopwatch = " + _callbackStopwatch.ElapsedMilliseconds + Environment.NewLine;

    }