Excel (mac) macro redirect to webpage extremely slow > HUH?!

Dear Experts,

I am running into an extremely annoying and strange problem. I hope someone can help me out with this, it drives me crazy by now! :s

I have the following macro:

Code:

---

Sub StuurNaarBoekhouding()

'Are you sure?
Antwoord = MsgBox("Sure?", vbOKCancel + vbExclamation, "WATCH IT!")
If Antwoord = vbCancel Then Exit Sub

'workbook save
ThisWorkbook.Save

'get modified date
Dim sLMD As String
    On Error Resume Next
    sLMD = ActiveWorkbook.BuiltinDocumentProperties("Last Save Time")
    If Err = 440 Then
        Err = 0
        sLMD = "0"
        ' not found so ask to save
        MsgBox "Not saved yet. Save it first.", vbOKOnly + vbCritical
        Exit Sub
    End If

'get filename
filelocation = ActiveWorkbook.FullName

'get extra info for url
Dim kostenplaats As String
kostenplaats = Worksheets("SHEETX").Range("C9:C9").Value
If kostenplaats = "" Then
    MsgBox "The extra value for the url is not set, fill in first.", vbOKOnly + vbCritical
    Exit Sub
End If

'create s code
Dim s As String
s = "coded_string_for_security_reasons"

'the url base
Dim url As String
url = "http://www.website.com/"

'UNTIL HERE, THE CODE WORKS FAST AS LIGHTING (tested by throwing an msgbox here)
'THE STEP DOWN HERE TAKES TWO (!!) MINUTES

'send to url
ActiveWorkbook.FollowHyperlink Address:=url + "?code=" + s + "&last_changed=" + sLMD + "&extra_info=" + kostenplaats + "&p=" + filelocation

'workbook save without saving again (so that saved last time info doesnt change)
ActiveWorkbook.Saved = True
ActiveWorkbook.Close SaveChanges:=False
End Sub

---

Now on windows, this piece of code works perfect. But on my mac (osx 10.8.3) office excel 2011 it does work, but the 'followhyperlink'-step takes 120 (!!) seconds to execute. This is extremely slow (on the windows it takes only 0.5 seconds or so).

What happens? How can I solve this problem?

I really hope that someone can help me out. Would be very very much appreciated!

S