It is very very simple to avoid p page refresh in post-back . To get this we just have to use ASP "Update Panel Control" it will not refresh the page again and again on post-back.


Here is an example.

In Default.aspx



<asp:UpdatePanel ID="pnlPageRefresh" runat="server">
        <ContentTemplate>
            <div>
                <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True">
                </asp:DropDownList>
                <br />
                <asp:TextBox ID="TextBox2" runat="server" AutoPostBack="True"></asp:TextBox>
                <asp:RadioButtonList ID="RadioButtonList1" runat="server" AutoPostBack="True">
                </asp:RadioButtonList>
            </div>
        </ContentTemplate>
    </asp:UpdatePanel>
<div>
<asp:Button ID="btnSave" runat="server" Text="Button" />
</div>


After using this your page will not at all refresh again and again on post-back. Your code will work fine but refresh flickering will not occur.