Please check the MS documentation on the copy functionality, as it seems to me that you are copying a sheet but pasting like a range: http://msdn.microsoft.com/en-us/libr...ice.11%29.aspx

apart from that, the fastest was to convert a formula result into a value:
    With Range(Cells(1, 1), Cells(5, 5))
        .Value = .Value
    End With
example for Activesheet Range A1:E5