Accélérer le code car très lent

With Sheets("A")
    .Range("j1").EntireColumn.Insert xlToLeft
    .Range("j2").FormulaR1C1 = "=RC[-2]&"" - ""&RC[-1]"
    .Range("j2").AutoFill Destination:=.Range("j2:j5000"), Type:=xlFillDefault
    .Columns("j:j").Copy
    .Columns("j:j").PasteSpecial Paste:=xlPasteValues
   Application.CutCopyMode = 0
End With

Sub test()
Dim derlig As Long, i As Long

With Sheets("A")
derlig = .Range("i" & Rows.Count).End(xlUp).Row
    For i = 2 To derlig
    .Range("j" & i).FormulaR1C1 = "=RC[-2]&"" - ""&RC[-1]"
    .Range("j" & i).Value = .Range("j" & i).Value
    Next i
End With
End Sub
'Au lieu de faire un AutoFill

Sub test_II()
Dim derlig&
With Sheets("A")
    derlig = .Range("i" & Rows.Count).End(xlUp).Row
    With .[J2].Resize(derlig - 1)
        .FormulaR1C1 = "=RC[-2]&"" - ""&RC[-1]"
        .Value = .Value
    End With
End With
End Sub