I have developped a VBA application in Excel which automates the process of
setting some part of the footer of newly created workbooks.

The problem I have is that the application becomes inexpectingly slow on
some machines. I identify that the following instruction is responsible for
the lack of performance:

Private Sub InsertClassification(iPageSetup As PageSetup, iLevel As String)
iPageSetup.LeftFooter = kFmt & iLevel & vbLf & iPageSetup.LeftFooter
End Sub

On some machines, it takes up to half a second to be executed, while it is
executed much faster on other.

Any idea ?

Thanks in advance