Beschleunigen des makros

Sub Makro1()
Set LastCell = ActiveSheet.Cells.SpecialCells(xlLastCell)
alta = LastCell.Row
A = LastCell.Row
Do While Application.CountA(Rows(A)) = 0 And A <> 1
A = A - 1
Loop
lzeile = A
For t1% = 1 To lzeile
If Range("a" & t1%) = "summe" And Range("o" & t1%) > 50 Or Range("a" & t1%) = "summe" And Range("q" & t1%) > 0 = "summe" And Range("o" & t1%) < -50 Then
st$ = Range("a" & t1% - 1)
Rows("" & t1% & ":" & t1%).Select
Selection.Delete Shift:=xlUp
lzeile = lzeile - 1
For et% = lzeile To 1 Step -1
If Range("a" & et%) = st$ Then
Rows("" & et% & ":" & et%).Select
Selection.Delete Shift:=xlUp
leile = lzeile - 1
End If
Next et%
End If
Next t1%
Range("a1").Select
End Sub