more effective script

Hi All,

Since I can't get my screen to lock in openoffice (while using VBA), I have to find another way to speed things up.
As you can see below, my scripting is very very poor and I was wondering how I can speed up the script.

I was thinking about tricks to let it run faster, but I don't really come up with solutions.

Sub Resetall()

Dim KZ As Worksheet
Dim VA As Worksheet
Dim ws As Worksheet
Dim iRow As Integer
Dim Rng As Range
Dim Aantal As Integer

Set ws = Worksheets("Data")
Set VA = Worksheets("HulpSheet")
Set KZ = Worksheets("Klanten")

Aantal = 0

lastRow = VA.Range("A:D").Find(What:="*", SearchOrder:=xlRows, SearchDirection:=xlPrevious, LookIn:=xlValues).Row + 1
For i = 2 To lastRow
 For j = 1 To 5
  VA.Cells(i,j).Value = ""
 Next j
Next i

lastRow = ws.Range("C:C").Find(What:="*", SearchOrder:=xlRows, SearchDirection:=xlPrevious, LookIn:=xlValues).Row + 1
For i = 3 To lastRow
iRow = VA.Range("A:A").Find(What:="*", SearchOrder:=xlRows, SearchDirection:=xlPrevious, LookIn:=xlValues).Row + 1
  If len(ws.Cells(i, 3).Value) > 1 then
  Rng = VA.Range("A:A").Find(What:=ws.Cells(i, 3).Value, SearchOrder:=xlRows, SearchDirection:=xlPrevious, LookIn:=xlValues)
    If not Rng is Nothing then 
    Set Rng = Nothing
    Else
    VA.Cells(iRow, 1).Value = ws.Cells(i, 3).Value
    End If
  End If
Next i

lastRow = ws.Range("D:D").Find(What:="*", SearchOrder:=xlRows, SearchDirection:=xlPrevious, LookIn:=xlValues).Row + 1
For i = 3 To lastRow
iRow = VA.Range("B:B").Find(What:="*", SearchOrder:=xlRows, SearchDirection:=xlPrevious, LookIn:=xlValues).Row + 1
  If len(ws.Cells(i, 4).Value) > 1 then
  Rng = VA.Range("B:B").Find(What:=ws.Cells(i, 4).Value, SearchOrder:=xlRows, SearchDirection:=xlPrevious, LookIn:=xlValues)
    If not Rng is Nothing then 
    Set Rng = Nothing
    Else
    VA.Cells(iRow, 2).Value = ws.Cells(i, 4).Value
    End If
  End If
Next i

lastRow = ws.Range("E:E").Find(What:="*", SearchOrder:=xlRows, SearchDirection:=xlPrevious, LookIn:=xlValues).Row + 1
For i = 3 To lastRow
iRow = VA.Range("C:C").Find(What:="*", SearchOrder:=xlRows, SearchDirection:=xlPrevious, LookIn:=xlValues).Row + 1
  If len(ws.Cells(i, 5).Value) > 1 then
  Rng = VA.Range("C:C").Find(What:=ws.Cells(i, 5).Value, SearchOrder:=xlRows, SearchDirection:=xlPrevious, LookIn:=xlValues)
    If not Rng is Nothing then 
    Set Rng = Nothing
    Else
    VA.Cells(iRow, 3).Value = ws.Cells(i, 5).Value
    End If
  End If
Next i

lastRow = ws.Range("H:H").Find(What:="*", SearchOrder:=xlRows, SearchDirection:=xlPrevious, LookIn:=xlValues).Row + 1
For i = 3 To lastRow
iRow = VA.Range("D:D").Find(What:="*", SearchOrder:=xlRows, SearchDirection:=xlPrevious, LookIn:=xlValues).Row + 1
  If len(ws.Cells(i, 8).Value) > 1 then
  Rng = VA.Range("D:D").Find(What:=ws.Cells(i, 8).Value, SearchOrder:=xlRows, SearchDirection:=xlPrevious, LookIn:=xlValues)
    If not Rng is Nothing then 
    Set Rng = Nothing
    Else
    VA.Cells(iRow, 4).Value = ws.Cells(i, 8).Value
    End If
  End If
Next i

Aantal = VA.Range("A:D").Find(What:="*", SearchOrder:=xlRows, SearchDirection:=xlPrevious, LookIn:=xlValues).Row + 1
KZ.Cells(3, 3).Value = ""
KZ.Cells(3, 4).Value = ""
KZ.Cells(3, 5).Value = ""
KZ.Cells(3, 6).Value = ""
KZ.Cells(6, 3).Value = ""
KZ.Cells(3, 8).Value = Aantal
Aantal = KZ.Cells.Find(What:=Aantal, SearchOrder:=xlRows, SearchDirection:=xlPrevious, LookIn:=xlValues).Row + 1 'to get back on worksheet("Klanten")

End Sub