Code itérant lentement

J'ai une macro simple qui crée 16 versions différentes d'un modèle, en mettant à jour en obtenant des valeurs d'un autre classeur ouvert. Cela prend plus d'une minute pour itérer seulement 16 fois et je me demandais s'il y avait un moyen d'accélérer le processus ? Cela va devenir un problème parce que j'ai besoin de l'itérer 64+ fois.

J'ai le sentiment que la raison pour laquelle mon code est lent est que j'accède trop souvent aux feuilles de calcul dans mes boucles. J'ai également cherché à réduire le nombre de comparaisons de chaînes de caractères, mais cela n'a pas semblé faire une grande différence.

Merci

Sub getORSA()
Application.ScreenUpdating = False

Dim wb As Workbook, template As Workbook
Dim ws As Worksheet, ws2 As Worksheet
Dim scenario As Variant, scenario2 As Variant, division As Variant, analysis As Variant
Dim a As Variant, b As Variant, c As Variant, confirm As Variant
Dim iterations As Integer
Dim templatePath As String, path As String, name As String, extension As String
Dim result As String
Dim timeOn As Date, timeOff As Date

'check the user wants to run script
confirm = MsgBox("Run ORSA script?", vbYesNo)
If confirm = vbNo Then
    Exit Sub
End If

timeOn = Now

'initialise variables & objects
Set wb = ThisWorkbook
Set ws = wb.Worksheets("T.change")
scenario = Array("Base") ' while testing use just one scenario
scenario2 = Array("Base", "Base (2)", "Inflation", "Deflation")
division = Array("LGAS SHF", "LGPL SHF", "SRC", "FINANCE")
analysis = Array("GROUP EC", "GROUP SII", "LGAS EC", "LGAS SII")

'template variables and open template
templatePath = "\\..."
path = "\\..."
name = "ORSA_"
extension = ".xlsx"
Set template = Workbooks.Open(Filename:=templatePath)

iterations = 0

    For Each a In scenario
        For Each b In division
            For Each c In analysis

                'update values on template
                With template.Worksheets("EB")

                    ' --SET HEADERS ON TEMPLATE -- '

                    .Range("C2").value = Trim(Right(c, 3))
                    .Range("G2").value = a
                    .Range("C4").value = "LGC"

                    Select Case b
                        Case "LGAS SHF", "SRC"
                            .Range("E4").value = "LGAS"
                        Case "LGPL SHF"
                            .Range("E4").value = "LGPL"
                        Case "FINANCE"
                            .Range("E4").value = "FIN PLC"
                     End Select

                    .Range("G4").value = "LGC"

                    Select Case b
                        Case "LGAS SHF", "LGPL SHF"
                            .Range("I4").value = "SHF"
                        Case "SRC"
                            .Range("I4").value = "SRC"
                        Case "FINANCE"
                            .Range("I4").value = "FIN_PLC"
                    End Select

                    ' -- SET VALUES ON TEMPLATE -- '

                    'update dropdowns of T.change tab
                    ws.Range("B1").value = a
                    ws.Range("B2").value = b
                    ws.Range("B3").value = c

                    Dim investmentReturn As Range
                    Dim capitalTransfer As Range
                    Dim cashSurplus As Range
                    Dim ifrsProfit As Range
                    Dim assets As Range

                    Set investmentReturn = ws.Range("C62:I62")
                    Set capitalTransfer = ws.Range("C64:I64")
                    Set cashSurplus = ws.Range("C65:I65")
                    Set ifrsProfit = ws.Range("C66:I66")
                    Set assets = ws.Range("C67:I72")

                    .Range("D17:J17").value = investmentReturn.value
                    .Range("D30:J30").value = capitalTransfer.value
                    .Range("D34:J34").value = cashSurplus.value
                    .Range("D46:J46").value = ifrsProfit.value
                    .Range("D52:J57").value = assets.value

                End With

                'save and close the template file
                template.SaveAs _
                Filename:=path & name & a & " - " & b & " - " & c & extension, _
                FileFormat:=xlOpenXMLWorkbook, CreateBackup:=False

                iterations = iterations + 1
            Next c
        Next b
    Next a

template.Close

timeOff = Now - timeOn

MsgBox ("Successfully ran " & iterations & " iterations" & vbNewLine _
    & "Time: " & Format(timeOff, "hh:mm:ss"))

Application.ScreenUpdating = True
End Sub

Pour plus de clarté, cet extrait est essentiel, car il modifie les valeurs de ma feuille maîtresse en fonction des valeurs qui doivent être saisies dans chaque version du modèle :

'update dropdowns of T.change tab
ws.Range("B1").value = a
ws.Range("B2").value = b
ws.Range("B3").value = c

Merci