Узнать, сколько по времени выполняется процесс

Dim P As New Process
        With P
            .StartInfo.FileName = "powershell.exe"
            .StartInfo.Arguments = "d:\скрипты\NetWorkSkan.ps1"
 
            .Start()
            .WaitForExit()
            MsgBox("Done")
        End With

    Dim _startTime As DateTime
    Const IntervalFormat As String = "mm':'ss"
 
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Button1.Enabled = False
        Label1.Text = TimeSpan.Zero.ToString(IntervalFormat)
        Label1.Visible = True
        Timer1.Enabled = True
        _startTime = DateTime.Now
        BackgroundWorker1.RunWorkerAsync()
    End Sub
 
    Private Sub BackgroundWorker1_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
        Using proc As New Process
            proc.StartInfo.FileName = "powershell.exe"
            proc.StartInfo.Arguments = "d:\скрипты\NetWorkSkan.ps1"
            proc.StartInfo.CreateNoWindow = True
            proc.StartInfo.WindowStyle = ProcessWindowStyle.Hidden
            proc.Start()
            proc.WaitForExit()
        End Using
    End Sub
 
    Private Sub BackgroundWorker1_RunWorkerCompleted(sender As Object, e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles BackgroundWorker1.RunWorkerCompleted
        Button1.Enabled = True
        Label1.Visible = False
        Timer1.Enabled = False
    End Sub
 
    Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
        Label1.Text = (DateTime.Now - _startTime).ToString(IntervalFormat)
    End Sub

Label1.Text = TimeSpan.Zero.ToString(IntervalFormat)