Sub sortbigdata()
      Dim Dict As Object, a(), i&, ii&, x&

      Set Dict = CreateObject("System.Collections.ArrayList")
      For i = 1 To 2
          a = Sheets(i).UsedRange.Columns(1).Value
          For ii = 1 To UBound(a)
              If Len(a(ii, 1)) Then Dict.Add CStr(a(ii, 1))
          Next
      Next
      Dict.Sort
      With Workbooks.Add(1)
          ReDim a(1 To Dict.Count / 2, 1 To 1)
          For i = 1 To UBound(a)
              a(i, 1) = Dict.Item(i - 1)
          Next
          x = i: ii = 0
          .Sheets(1).[a1].Resize(UBound(a), 1) = a
          .Sheets.Add after:=.Worksheets(1)
          ReDim a(1 To Dict.Count / 2, 1 To 1)
          For i = x To Dict.Count
              ii = ii + 1
              a(ii, 1) = Dict.Item(i - 1)
          Next
          .Sheets(2).[a1].Resize(UBound(a), 1) = a
      End With
End Sub