I need to delete rows if sheet1 Column F not equal to Sheet3 G5:G10

I tried below code, but it works very very slow.. Actually there are around
25000+ records..

sub deleterows()
Set MySheet = Sheets("Sheet1")
LR = MySheet.Cells(Rows.Count,"F").End(xlup).Row
For i = LR to 2 Step -1
With Sheets("Sheet3")
If WorksheetFunction.Countif(.Range("G5:G10"),MySheet .Cells(i,"F"))0 Then
MySheet.Rows(i).EntireRow.Delete
End If
End With
Next i
End Sub


Any better one..?