Public Class RTTimer
 
    Public Event Elapsed(ByVal sender As Object, ByVal e As Results)
    Dim WithEvents worker1 As New System.ComponentModel.BackgroundWorker
    Dim Owner As Form
    Dim EventData As Results
    Dim IsRunning As Boolean
 
    Public Structure Results
        Dim ScannZeit As Long
    End Structure
 
    Private Delegate Sub ScannCompleted_DelegateObject(ByVal Data As Results)
    Private Sub Sub_ScannComplete(ByVal e As Results)
        If Owner.InvokeRequired Then
            Dim dd As New ScannCompleted_DelegateObject(AddressOf _
              Sub_ScannComplete)
            Owner.Invoke(dd, New Object() {e})
        Else
            RaiseEvent Elapsed(Me, e)
        End If
    End Sub
 
    Sub New(ByVal Parent As Form)
        Owner = Parent
    End Sub
 
    Public Sub Start(ByVal interval As Integer)
        If IsRunning = False Then
            worker1.WorkerSupportsCancellation = True
            worker1.RunWorkerAsync(interval)
        End If
    End Sub
 
    Public Sub Cancel()
        If IsRunning = True Then worker1.CancelAsync()
    End Sub
 
    Public Function IsBusy() As Boolean
        IsBusy = worker1.IsBusy
    End Function
 
    Private Sub RunWorker1(ByVal sender As Object, ByVal e As _
      System.ComponentModel.DoWorkEventArgs) Handles worker1.DoWork
        IsRunning = True
        Dim watch As New Stopwatch
        Dim interval As Integer = Convert.ToInt32(e.Argument)
redo:
        watch.Reset()
        watch.Start()
        Do
            If worker1.CancellationPending = True Then GoTo endSub
            If watch.ElapsedMilliseconds >= interval Then
                Dim EventData As New RTTimer.Results
                EventData.ScannZeit = watch.ElapsedMilliseconds
                Sub_ScannComplete(EventData)
                Exit Do
            End If
 
        Loop
        GoTo redo
        IsRunning = False
endSub:
    End Sub
 
 
End Class

Dim WithEvents EchtZeitTimer As New RTTimer(Me)
Dim cnt As Integer = 0
 
 
    Private Sub EchtZeitTimer_Elapsed(ByVal sender As Object, ByVal e As _
      RTTimer.Results) Handles EchtZeitTimer.Elapsed
        cnt += 1
        Me.Text = Date.Now & ": " & e.ScannZeit.ToString & " - " & cnt
        If e.ScannZeit > 8 Then
            ListBox1.Items.Add(Date.Now & ": " & e.ScannZeit.ToString & " - " & _
              cnt)
        End If
    End Sub
 
    Private Sub Button_Stop__Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button_Stop.Click
        EchtZeitTimer.Cancel()
    End Sub
 
    Private Sub Button_Start_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button_Start.Click
        EchtZeitTimer.Start(8)
    End Sub