Optimise VBA Code for SUMPRODUCT analysis

I would welcome any thoughts, ideas or suggestions as to how I can optimise the VBA code listed below.

This is running on Windows XP/Excel 2003 on a Toshiba Portege laptop with 512 Mb RAM

I am trying to analyse the contents of a worksheet. To that end, I have created a matrix on another sheet. This matrix is 117 columns wide by 232 rows deep and is/was populated by SUMPRODUCT formulae. The SUMPRODUCT formula works and gives the correct results but the sheer volume made the worksheet/workbook unusable.

To overcome the impact on the rest of the workbook, I had copied the formulae and pasted the values back. I now want to revisit the calculation and add another criteria.

Initially, I just edited the formula and copied and pasted it to the rest of the matrix ... but the workbook appeared to hang. I decided then to use VBA to insert the formulae a column at a time and copy and paste the values. However, this process is taking around 7 to 9 seconds per column. What is worse, if I just let it run, it seems to hang.

I can nurse the code through and it works but I could do without sitting for 15 minutes or so every time I run it. I have other sheets I will want to do similar analyses with so it's not just idle interest.

Sub Analyse_AR()

Dim calcState
Dim lLRow As Long
Dim lLCol As Long
Dim lLC As Long

If ActiveSheet.Name <> "Analysis (ar)" Then
    MsgBox "Select Analysis (ar) Sheet"
    Exit Sub
End If

Application.ScreenUpdating = False
calcState = Application.Calculation
Application.Calculation = xlCalculationManual

lLRow = Range("B" & Rows.Count).End(xlUp).Row - 1
lLCol = Cells(1, Columns.Count).End(xlToLeft).Column - 1
    
For lLC = 2 To lLCol
    Debug.Print lLC; "  start "; Now()
    With Range(Cells(3, lLC), Cells(lLRow, lLC))
        .FormulaR1C1 = _
            "=SUMPRODUCT(('No 1 '!R2C7:R6600C7=RC1)*('No 1 '!R2C3:R6600C3=R1C)*('No 1 '!R2C11:R6600C11=""ar""))"
        Application.Calculate
        .Copy
        .PasteSpecial _
            Paste:=xlPasteValues
        Application.CutCopyMode = False
    End With
    Debug.Print lLC; "  end "; Now()
Next 'lLC

Application.Calculation = calcState
Application.ScreenUpdating = True

End Sub

Thanks in advance for any help or guidance you can offer.

Regards