Why does timer code (by dbasnett) no longer work splendidly?

Question

Using timer code supplied by dbasnett back in May2014, I was able to see FPS of near 500 for a simple animation. Now, with a more recent 64bit laptop Win 8.1 - -  I run the same code - - - and see poor results similar to standard timers - - where the
results are "stepped" - - -like either 16FPS or 32FPS or the max I can get is 64FPS.
This thread back in May2014  - -https://social.msdn.microsoft.com/Forums/vstudio/en-US/9ddb2f16-796a-483a-aa3f-0f9b959e0eea/the-use-of-systemwindowsformstimer-for-time?forum=vbgeneral
And here is the code that dbasnett supplied - -
Public Class Form1
Dim R As Integer
Dim D, T As Double
Private Sub Form1_Load(sender As Object, e As System.EventArgs) Handles Me.Load
Me.ClientSize = New Size(500, 500)
Me.DoubleBuffered = True
T = Environment.TickCount
timeSubThrd = New Threading.Thread(AddressOf timeSub)
timeSubThrd.IsBackground = True
timeSubThrd.Start()
End Sub
Private Sub Form1_FormClosing(sender As Object, e As FormClosingEventArgs) Handles Me.FormClosing
If Not slp.WaitOne(0) Then
'RemoveHandler Me.Paint, AddressOf Me.Form1_Paint
slp.Set()
e.Cancel = True
End If
End Sub
Private Sub Form1_Paint(sender As Object, e As System.Windows.Forms.PaintEventArgs) Handles Me.Paint
Dim rct As Rectangle = New Rectangle(250 - R, 250 - R, 2 * R, 2 * R)
Using spen As New Pen(Color.FromArgb(83, 32, 69))
spen.Width = 4
e.Graphics.DrawEllipse(spen, rct)
End Using
End Sub
Dim timeSubThrd As Threading.Thread
Dim slp As New Threading.ManualResetEvent(False)
Private Sub timeSub()
Dim A As Double = -1
Do
D += 0.125663707
If D > (2 * Math.PI) Then
A = 50000 / (Environment.TickCount - T)
T = Environment.TickCount
D = 0
End If
R = CInt(Math.Cos(D) * 60) + 180
Me.Invoke(Sub()
Invalidate()
If A <> -1 Then
Me.Text = A.ToString("##0.0##") & " FPS"
End If
End Sub)
A = -1
Loop While Not slp.WaitOne(20) '<<<<<<< the timer interval
Me.Invoke(Sub()
Me.Close()
End Sub)
End Sub
End Class
With timer interval set to 20 - - - - it used to give about 50FPS (which is should), but it doesnt anymore - - - it gives 32FPS.
Can anybody shed some light on what has gone wrong? My present laptop also a I7 is 4 years younger than my old laptop and has far betters specs. Why is it slower? or why is this timer code no longer acting the same?
Thanks
Leon Stanley - ♪Don't pay the ferryman - till he gets you over to the other side♪ . um . I apply this to corporations - not to God.

Answer 1

@ Reed Kimble. Thanks for your point about not being OS related. That make sense anyway.
@ Mr.Monkeyboy. Thanks for your links and points. I had a bit of a read. Mostly over my head. To me it should'nt be a thread priority question because the program is so simple - there is only one thread anyway.
And I don't think it is a graphics issue, because I altered the program to only manipulate a bitmap - not activate a paint event -  - - but it still performs poorly. I only get 32 Cycles Per Second instead of 50 CPS. See - this is how I altered the
code - but no change in performance:-
Public Class Form4
Dim bmp As Bitmap
Dim gfx As Graphics
Dim R As Integer
Dim D, T As Double
Private Sub Form4_Load(sender As Object, e As System.EventArgs) Handles Me.Load
bmp = New Bitmap(500, 500)
gfx = Graphics.FromImage(bmp)
Me.ClientSize = New Size(500, 500)
T = Environment.TickCount
timeSubThrd = New Threading.Thread(AddressOf timeSub)
timeSubThrd.IsBackground = True
timeSubThrd.Start()
End Sub
Private Sub Form2_FormClosing(sender As Object, e As FormClosingEventArgs) Handles Me.FormClosing
If Not slp.WaitOne(0) Then
'RemoveHandler Me.Paint, AddressOf Me.Form2_Paint
slp.Set()
e.Cancel = True
End If
End Sub
Sub test()
Dim rct As Rectangle = New Rectangle(250 - R, 250 - R, 2 * R, 2 * R)
Using spen As New Pen(Color.FromArgb(83, 32, 69))
spen.Width = 4
gfx.DrawEllipse(spen, rct)
End Using
End Sub
Dim timeSubThrd As Threading.Thread
Dim slp As New Threading.ManualResetEvent(False)
Private Sub timeSub()
Dim A As Double = -1
Do
D += 0.125663707
If D > (2 * Math.PI) Then
A = 50000 / (Environment.TickCount - T)
T = Environment.TickCount
D = 0
End If
R = CInt(Math.Cos(D) * 60) + 180
Me.Invoke(Sub()
test()
If A <> -1 Then
Me.Text = A.ToString("##0.0##") & " CPS"
End If
End Sub)
A = -1
Loop While Not slp.WaitOne(20) '<<<<<<< the timer interval
Me.Invoke(Sub()
Me.Close()
End Sub)
End Sub
End Class
PS - I changed the code so that it does not deal with bitmaps or graphics at all - - - but still no improvement.
Maybe it is Framework Version issue ??
Thanks all
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