Json deserialize list vs datatable (several cases) - json

Question

I have the following json:
{
"Header": {
"MCC": "415",
"FO": "0",
"REGID": "5"
},
"Contacts": [
{
"NAME": "jocelyne",
"MO": "70123456"
},
{
"NAME": "eliane",
"MO": "03123456"
}
] }
I have 2 clients: one client is giving me this json in this order, the second is giving me the mo before name in the json, but I need to have the same order in the datatable all the time when I deserialize the json.
What I need to know which is the better way?
1-to deserialize the json in a list (it takes the tags in the alphabetic order) and then convert the list to a datatable
in this case that's what i'm doing:
Public Class Dataa
Public MCC As Integer
Public FO As Integer
Public RegId As Integer
Public Contacts As Contacts()
End Class
<Serializable()> _
Public Class Contacts
Public name As String
Public mo As String
End Class
Dim jss As New JavaScriptSerializer
Dim oFareResults As Generic.List(Of Dataa) = jss.Deserialize(Of List(Of Dataa))(json)
contactsDT = ConvertListToDataTable(oFareResults)
contactsDT.Columns.Add("taken_mo", GetType(String))
contactsDT.Columns.Add("reg_id", GetType(Integer))
Private Shared Function ConvertListToDataTable(oFareResults As List(Of Dataa)) As DataTable
' New table.
Dim dtTable As New DataTable()
dtTable.Columns.Add("name", GetType(String))
dtTable.Columns.Add("mo", GetType(String))
For i As Integer = 0 To oFareResults.Item(0).Contacts.Length - 1
dtTable.Rows.Add(oFareResults(0).Contacts(i).name, oFareResults(0).Contacts(i).mo)
Next
Return dtTable
End Function
2-to select 2 cases, every case for a different client and then deserialize the json in a datatable
in this case:
Public Class Data
Public Header As Header
Public Contacts As DataTable
End Class
<System.Runtime.Serialization.DataContract()>
Public Class Header
<System.Runtime.Serialization.DataMember(Name:="MCC")>
Public MCC As Integer
<System.Runtime.Serialization.DataMember(Name:="FO")>
Public FO As Integer
<System.Runtime.Serialization.DataMember(Name:="REGID")>
Public RegId As Integer
End Class
Dim data As New Data
data = JsonConvert.DeserializeObject(Of Data)(json)
mcc = data.Header.MCC
FO = data.Header.FO
regid = data.Header.RegId
contactsDT = data.Contacts
that's how i have to deserialize the json into a datatable and in this case i have to have 2 functions to deserialize one for every client ( to reserve the order that i need)
Well, what I need to know is not the general solution but I need to know which one has a better performance for the server considering that my json may be very long.
so i need the advantages and disadvantages of each case