VBA 按列查找小工具类似lookUp函数

如上图，查找A列的数据在D,F列是否存在，如果存在背景色变绿，如果不存在则A列的背景色变红。

直接贴上代码：

Private Sub CommandButton1_Click()
    Call lookUpAToDF
End Sub

Public Sub lookUpAToDF()
   Dim a, d, f As Long
   'Count of non-empty data in colum A,D,F
   a = Application.WorksheetFunction.CountA(Range("A:A"))
   d = Application.WorksheetFunction.CountA(Range("D:D"))
   f = Application.WorksheetFunction.CountA(Range("F:F"))
   Dim ac, dc, fc As Integer
   'loop the A
   For ac = 1 To a Step 1
       Dim aTxt As String
       ' get column A value
       aTxt = TrimSpace(Cells(ac, 1).Text)
       If aTxt = "" Then
           Exit For
       End If
       ' add flg var for switch selected aTxt
       Dim flg As Boolean
       flg = True
       For dc = 1 To d Step 1
           Dim dTxt As String
           dTxt = TrimSpace(Cells(dc, 4).Text)
           If aTxt = dTxt Then
               flg = False
               Exit For
           End If
       Next dc
       'if column D selected result is empty then
       'loop the colum F
       If flg Then
           For fc = 1 To f Step 1
               Dim fTxt As String
               fTxt = TrimSpace(Cells(fc, 6).Text)
               If aTxt = fTxt Then
                   flg = False
                   Exit For
               End If
           Next fc
       End If
       If flg Then
           Cells(ac, 1).Interior.ColorIndex = 3 'red
       Else
           Cells(ac, 1).Interior.ColorIndex = 4 'green
       End If
   Next ac
   MsgBox "find completed!"
End Sub
Public Function TrimSpace(strItem As String) As String
   Dim resultStr As String
   resultStr = LTrim(strItem)
   resultStr = RTrim(resultStr)
   TrimSpace = resultStr
End Function

代码还没有优化，行数达到10000+的时候会有卡顿。