Here is my last revision of snb's code.

I am still concerned about speed for M. I have seen this code run slow the 1st time but after that it ran fast. ADO might be another route but it often run's slow too.

You will notice that I like to use Option Explicit so I added Dim accordingly. I also like to use early bound methods for the FSO object but I know many like the late bound method so I left it with the intent not to change snb's code too much which might confuse you. I also added the concept that Sam used where the full filename was trimmed to the basename. 

Option Explicit



Sub M_snb3()
  Dim sn() As String, c00() As String, j As Long, jj As Long
  Dim sp() As String, y As Double


  sn = Filter(Split(CreateObject("wscript.shell").exec _
    ("cmd /c Dir ""X:\snb\maxxino\*.csv"" /b /s").stdout.readall, vbCrLf), ".")
    
  ReDim c00(1 To UBound(sn) + 1, 1 To 2) As String
    
  With CreateObject("scripting.filesystemobject")
    For j = 0 To UBound(sn)
      y = 0
      sp = Split(.opentextfile(sn(j)).readall, vbCrLf)
       
      For jj = 0 To UBound(sp) - 1
        sp(jj) = Log(Split(sp(jj), ",")(5)) / Log(10)
        If jj > 0 Then y = y + 100 * (sp(jj) - sp(jj - 1)) ^ 2
      Next jj
      'c00(j + 1, 1) = sn(j)                'CSV Full Filename
      c00(j + 1, 1) = .GetBasename(sn(j)) 'CSV Base Filename
      c00(j + 1, 2) = y                    'Result
    Next j
  End With
    
  Range("A1").Resize(UBound(c00), 2).Value = c00
  Columns("A:B").AutoFit
End Sub