Excecute a lot, withouth timeout, and real progress

I've build a code witch is executing a lot of code.
Right now in the testing part there is no time out, but i think if i execute 100x times bigger data, i've get a timeout.
So wat i want, executing a lot of data, and for every execution i like to print a row.

I tough i could do it with ajax but it doenst work, the rows are there after he executed it...
Current solution:
 
ASPX file:
<asp:UpdatePanel ID="UpdateNieuwsbrief" runat="server"> <ContentTemplate> <asp:Panel ID="PanelMain" runat="server" CssClass="panel"> <div class="bl"><div class="br"><div class="tl"><div class="tr"> <asp:Label ID="lblGroepenHeader" runat="server" CssClass="red" Text="Verzonden" ...