Calculate distance between two addresses

Hello everyone
I have the following UDF that calculates the distance between two addresses

Public Function GetDistance(start As String, dest As String)
    Dim firstVal As String, secondVal As String, lastVal As String
    firstVal = "http://maps.googleapis.com/maps/api/distancematrix/json?origins="
    secondVal = "&destinations="
    lastVal = "&mode=car&language=pl&sensor=false"
    Set objHTTP = CreateObject("MSXML2.ServerXMLHTTP")
    URL = firstVal & Replace(start, " ", "+") & secondVal & Replace(dest, " ", "+") & lastVal
    objHTTP.Open "GET", URL, False
    objHTTP.setRequestHeader "User-Agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)"
    objHTTP.send ("")
    If InStr(objHTTP.responseText, """distance"" : {") = 0 Then GoTo ErrorHandl
    Set regex = CreateObject("VBScript.RegExp"): regex.Pattern = """value"".*?([0-9]+)": regex.Global = False
    Set matches = regex.Execute(objHTTP.responseText)
    tmpVal = Replace(matches(0).SubMatches(0), ".", Application.International(xlListSeparator))
    GetDistance = CDbl(tmpVal)
    Exit Function
ErrorHandl:
    GetDistance = -1
End Function

But it is very slow and most of the time it doesn't return correct results ..
There is a sample of the origonal file .. the original file has more then 15000 addresses ..
Is there a faster way ?