DataGrid / DataTable Speed Question

I have a speed issue when adding to a DataGrid. The first time I add about 200 rows it take < 1 second. The second time I add 200 rows it takes about 10 seconds. Why is this?

I am wondering if I am not leaving the grid or table in a proper state the first time thru? Please help if you have any ideas - thanks.


Here is the appropriate snippet of code:

Code:

---

    Private Sub ButtonDisplay_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ButtonDisplay.Click
        Dim StartId As Int32 = CInt("&H" & TextBoxStartId.Text)
        Dim StopId As Int32 = CInt("&H" & TextBoxStopId.Text)
        Dim myRow As DataRow

        DataGrid1.Enabled = False
        dtMessage.BeginLoadData()
        DataGrid1.BeginInit()
        Cursor.Current = System.Windows.Forms.Cursors.WaitCursor

        For i As Int32 = StartAddr To StopAddr Step StepSize
            myRow = dtMessage.NewRow()

            myRow(gMessageTime) = gAscFile(0).RxMsgs(i).Time
            myRow(gMessageChannel) = gAscFile(0).RxMsgs(i).Channel
            myRow(gMessageName) = gAscFile(0).RxMsgs(i).IdMsg
            myRow(gMessageId) = Hex(gAscFile(0).RxMsgs(i).Id)
            myRow(gDcl) = gAscFile(0).RxMsgs(i).Dlc
            myRow(gLine) = gAscFile(0).RxMsgs(i).Line
            myRow(gEcu) = gAscFile(0).RxMsgs(i).Transmitter

            Dim Mg As String = ""
            For j As Int16 = 0 To gAscFile(0).RxMsgs(i).Dlc - 1
                If gAscFile(0).RxMsgs(i).Msg(j) < 16 Then
                    Mg += "0" & Hex(gAscFile(0).RxMsgs(i).Msg(j)) + "  "
                Else
                    Mg += Hex(gAscFile(0).RxMsgs(i).Msg(j)) + "  "
                End If
            Next
            myRow(gMessage) = Mg

            dtMessage.Rows.Add(myRow)
 
        Next

        dtMessage.EndLoadData()

        dtMessage.AcceptChanges()
        DataGrid1.EndInit()

        ButtonDisplay.Enabled = True
        ButtonSave.Enabled = True
        ButtonClear.Enabled = True
        ButtonRemove.Enabled = True
        ComboBoxChannel.Enabled = True
        DataGrid1.Enabled = True
        UpdateGridLines()
        Me.Enabled = True
        Cursor.Current = System.Windows.Forms.Cursors.Default
    End Sub

---

SOLVED!!!!

I created an empty data table and assigned that to the data grid. Then I add my new rows to the existing data table. When done adding the data newly modified data table back to the data grid.