XL 2016 Compteur avec conditions

Private Sub Worksheet_Change(ByVal Target As Range)
Dim Cell As Range
    If Not Intersect(Target, Columns("K")) Is Nothing Then
        For Each Cell In Target.Cells
            Application.EnableEvents = False
            Cell = UCase(Cell)
            Select Case Cell
                Case "N": Cell.Offset(0, -4) = Cell.Offset(0, -4) + 1
                Case "O": Cell.Offset(0, -4) = 0
                Case Else:   ' Rien
            End Select
            Application.EnableEvents = True
        Next
    End If
End Sub

Option Explicit

Sub Essai()
  Dim nlm&, n&: nlm = Rows.Count
  n = Cells(nlm, 1).End(3).Row: If n = 1 Then Exit Sub
  Dim Tbl, ft$, t%, k As Byte, i&: Application.ScreenUpdating = 0
  n = n - 1: [G2].Resize(n) = Empty: [K2].Resize(n, 2) = Empty
  n = Cells(nlm, 9).End(3).Row: If n = 1 Then Exit Sub
  n = n - 1: Tbl = [G2].Resize(n, 6)
  For i = 1 To n
    ft = Tbl(i, 3)
    If ft <> "" Then
      k = -(ft = "0 - 0")
      Tbl(i, 5) = Chr$(79 - k): Tbl(i, 6) = k
      If k = 0 Then t = 0 Else t = t + 1
      Tbl(i, 1) = t
    End If
  Next i
  [G2].Resize(n) = Application.Index(Tbl, Evaluate("Row(" & "1:" & n & ")"), 1)
  [K2].Resize(n, 2) = Application.Index(Tbl, Evaluate("Row(" & "1:" & n & ")"), _
    [Column(E:F)])
End Sub