Takes Too Long ‘calculating Cells’

This code is taking way too long to display the actions that it executes. It didn’t used to be that way. I was wondering if anyone knows why this may be. The Excel file is large – over 8 MB.

Private Sub Worksheet_Change(ByVal Target As Range)
Const WS_RANGE As String = "N:N"
Dim Cmnt
On Error Goto ws_exit:
Application.EnableEvents = False
If Not Intersect(Target, Me.Range(WS_RANGE)) Is Nothing Then
With Target
If .Row > 3 Then
If Me.Cells(.Row, "N").Value = "" Or Me.Cells(.Row, "N").Value = "O" Or Me.Cells(.Row, "N").Value = "H" Then
Me.Cells(.Row, "A").Resize(, 26).Interior.ColorIndex = 0
End If
If Me.Cells(.Row, "N").Value = "C" And Me.Cells(.Row, "O").Value = "DR" Then
Me.Cells(.Row, "A").Resize(, 26).Interior.ColorIndex = 39
End If
If Me.Cells(.Row, "N").Value = "C" And Me.Cells(.Row, "O").Value = "HJB" Then
Me.Cells(.Row, "A").Resize(, 26).Interior.ColorIndex = 6
End If.....................................