Question

From the performance view, is it better to check or not to check for Nothing(null) before set it?

Is clear that for readability maybe there is no need of supplementary step, but for performance? Maybe testing the IF is less time consuming that setting to NULL, if there is no need of?!

I run that on a computer, and the result was the same.

  Dim sw As New Stopwatch()

  sw.Start()
  For i As Integer = 0 To 10000
    _MyObject = Nothing
  Next

  sw.Stop()
  Console.WriteLine("no check: {0}", sw.Elapsed)
  sw.Reset()

  sw.Start()
  For i As Integer = 0 To 10000
    If _MyObject IsNot Nothing Then
      _MyObject = Nothing
    End If
  Next

  sw.Stop()
  Console.WriteLine("with check: {0}", sw.Elapsed)

Result:

no check: 00:00:00.0000326
with check: 00:00:00.0000349

Answer 1

There really is no logical reason to check if the value is already null/Nothing. As you can see you take a small hit in performance with the check anyway.