How to optimise counting in loops

Hi, so I have a macro that takes an hour to process and I have an idea why but I do not know how to optimise it. If anyone can, can you please help?

Thank you!

Sub Example4()
Dim mcco As Worksheet, mcfc As Worksheet, mcfb As Worksheet, mcfv As Worksheet
Dim CVTR As Long, FCBR As Long, FBCC As Long, FCMC As Long, ii As Long, i As Long, j As Long, k As Long, l As Long, s As Long
Dim FTVA(), FTNA, MLNA
Dim CVFD As Collection, CVMN As Collection, CVFP As Collection, CVFN As Collection, CVM1 As Collection, CVM2 As Collection
Dim XD
Dim pattern As String

Application.ScreenUpdating = False
Application.Calculation = xlCalculationManual

Set mcco = Workbooks("PERSONAL.xlsb").Worksheets("Converter")
Set mcfc = Workbooks("PERSONAL.xlsb").Worksheets("Files Count")
Set mcfb = Workbooks("PERSONAL.xlsb").Worksheets("Files BSA Converter")
  
CVTR = mcco.Cells(Rows.Count, 2).End(xlUp).Row 'Currently at 400439
FCBR = mcfc.Cells(Rows.Count, 2).End(xlUp).Row - 1 'Currently at 870
FBCC = Application.WorksheetFunction.Max(mcfc.Columns(6)) + 1 'Currently at 5
FCMC = mcfc.Cells(1, Columns.Count).End(xlToLeft).Column 'Currently at 41

Workbooks("PERSONAL.xlsb").Worksheets("Converter").Activate

Set CVFD = New Collection
Set CVMN = New Collection
Set CVFP = New Collection
Set CVFN = New Collection
Set CVM1 = New Collection
Set CVM2 = New Collection

For i = 1 To CVTR
    CVFD.Add mcco.Cells(i, 1).Value
    CVMN.Add mcco.Cells(i, 2).Value
    CVFP.Add mcco.Cells(i, 3).Value
    CVFN.Add mcco.Cells(i, 4).Value
    CVM1.Add mcco.Cells(i, 2).Value & " || " & mcco.Cells(i, 3).Value
    CVM2.Add mcco.Cells(i, 2).Value & " || " & mcco.Cells(i, 4).Value
Next i

MLNA = Application.Transpose(Range(mcfc.Cells(1, 2), mcfc.Cells(FCBR, 2)))

j = 1
With mcfc
    FTNA = Application.Transpose(.Range(.Cells(1, 1), .Cells(1, FCMC)).Value)
    For i = 3 To FCMC
        ReDim Preserve FTVA(j)
        FTVA(j) = Mid(FTNA(i, 1), Application.Find("(", FTNA(i, 1)) + 1, Application.Find(")", FTNA(i, 1)) - Application.Find("(", FTNA(i, 1)) - 1)
        j = j + 1
    Next i
End With
    
    For j = 1 To FCBR
        c = 0
        For k = 3 To 7
            For l = 2 To CVTR
            pattern = "*" & MLNA(j) & "*" & FTVA(k) & ""
            If CVM2.Item(l) Like pattern Then
                mcfc.Cells(j + 1, k).Value = c + 1
                c = mcfc.Cells(j + 1, k).Value
            End If
            Next l
            Stop
        Next k
    Next j

Stop
Application.ScreenUpdating = True
Application.Calculation = xlCalculationManual

End Sub