Sub Remplissage()
Dim t, P As Range, tablo, i&
t = Timer
Set P = Intersect([A:A], ActiveSheet.UsedRange.EntireRow)
tablo = P.Resize(P.Rows.Count + 1) 'au moins 2 éléments
For i = 2 To P.Rows.Count
If tablo(i, 1) = "" Then tablo(i, 1) = tablo(i - 1, 1)
Next
P = tablo
MsgBox "Durée " & Format(Timer - t, "0.00 \s") 'mesure facultative
End Sub