Sub MAJ()
Dim F As Worksheet, P As Range, tablo, ncol%, colref As Range, i&, j%
Set F = Sheets("Yx")
Set P = Sheets("synthèse").[C6].CurrentRegion 'à adapter éventuellement
tablo = P 'matrice, plus rapide
ncol = UBound(tablo, 2)
With F.[A8].CurrentRegion 'à adapter éventuellement
Set colref = .Columns(.Columns.Count).Cells
End With
For i = 2 To UBound(tablo)
F.Range("B4") = tablo(i, 1)
For j = 2 To ncol
If Not IsError(colref(j)) Then tablo(i, j) = colref(j)
Next j, i
P = tablo 'restitution
F.Range("B4") = tablo(2, 1)
End Sub