Sub test()
Dim t, res(1 To 100000, 1 To 2), i&, j&, n&
Application.ScreenUpdating = False
t = Range("a1").CurrentRegion
For i = 1 To UBound(t)
For j = t(i, 1) To t(i, 2)
If n = UBound(res) Then Cells(Rows.Count, 1).End(xlUp).Offset(1).Resize(n, 2) = res: n = 0
n = n + 1: res(n, 1) = j: res(n, 2) = t(i, 3)
Next j
Next i
If n > 0 Then Cells(Rows.Count, 1).End(xlUp).Offset(1).Resize(n, 2) = res
Cells(1, 1).Resize(UBound(t), 3).Delete xlShiftUp
Cells(1, 1).Resize(Cells(Rows.Count, 1).End(xlUp).Row).NumberFormat = "dd/mm/yyyy"
End Sub