Code running really slowly

Sorry - missed an end if:

Sub Caseware()
Dim rngtodelete as range
Application.ScreenUpdating = False
Application.Calculation = xlManual
Dim i As Long

For i = Cells(Rows.Count, "a").End(xlUp).Row To 2 Step -1
If Cells(i, "e") = 0 Then
If rngtodelete is nothing then
Set rngtodelete = cells(I, " e")
Else 
Set rngtodelete = union(rngtodelete, cells(I, "e"))
End if
End if
Next i
If not rngtodelete is nothing then rngtodelete.entirerow.delete
End Sub