Medir el tiempo transcurrido

Dim watch As Stopwatch = Stopwatch.StartNew
watch.Start()
' código aquí...
watch.Stop()

TextBox1.Text = watch.Elapsed.TotalSeconds

 Dim ts As TimeSpan = watch.Elapsed
 results = String.Format("{0} minute(s)" & " {1} second(s)" & " {2} milesconds(s)", 

ts.Minutes, ts.Seconds, ts.Milliseconds)

watch.Reset