I write a simple code with Timer. but when I start timer and then when I try to move form with mouse dawn or when I try to click a Button response with delayed.

What I am doing Wrong ?

Code:
Public Class Form3
    Dim _RGB As Integer
    Dim renk As Color
    Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
        Dim hiz As Double
        hiz = -0.4

        For i = 256 To 0 Step hiz
            _RGB = RGB(i, 0, 0) 'VScrollBar1.Value, 0, 0) ', VScrollBar2.Value, VScrollBar3.Value)
            renk = ColorTranslator.FromOle(_RGB)
            'RectangleShape1.FillColor = renk
            PictureBox1.BackColor = renk
            PictureBox1.Refresh()
        Next i

        For i = 256 To 0 Step hiz
            _RGB = RGB(0, i, 0) 'VScrollBar1.Value, 0, 0) ', VScrollBar2.Value, VScrollBar3.Value)
            renk = ColorTranslator.FromOle(_RGB)
            'RectangleShape1.FillColor = renk
            PictureBox2.BackColor = renk
            PictureBox2.Refresh()
        Next i

        For i = 256 To 0 Step hiz
            _RGB = RGB(0, 0, i) 'VScrollBar1.Value, 0, 0) ', VScrollBar2.Value, VScrollBar3.Value)
            renk = ColorTranslator.FromOle(_RGB)
            'RectangleShape1.FillColor = renk
            PictureBox3.BackColor = renk
            PictureBox3.Refresh()
        Next i



    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

        If Timer1.Enabled = False Then
            Timer1.Start()
        Else
            Timer1.Stop()
        End If
    End Sub
End Class