Event Handler And Redirecting From URL With QueryString

I have a page request with a QueryString, say [URL]. The page is displayed in a browser. Now there is an asp:LinkButton on the page which should enable the user to open the page without the QueryString (as if he had entered [URL] directly in the browser's address bar). I had two ideas:

1) Use the PostBackUrl attribute of the LinkButton:
<asp:LinkButton ID="LinkButton1" runat="server" Text="Select" PostBackUrl="~/Orders.aspx" />

2) Use "RedirectUrl" in an event handler:
<asp:LinkButton ID="LinkButton1" runat="server" Text="Select" OnClick="LinkButton1_Click" />
and
protected void LinkButton1_Click(object sender, EventArgs e) {
Response.Redirect("~/Orders.aspx"); }

In both cases the browser's address bar shows [URL] without the QueryString, as I like to have it. But in the first case the page does not change at all. But it should, because I'm evaluating the QueryString in code-behind and control the appearance of the page depending on whether a QueryString exists or not. The second option works as intended. If I am not wrong the second option requires an additional roundtrip:

Browser sends request to server
Event handler on server side sends Redirect URL to browser
Browser sends again request to the server, but with the new URL
Server sends new requested page to browser

Whereas the first option omits the first two steps in the list above, thus saving the additional roundtrip and resulting in: Browser sends request to the server, but with the new URL (the PostbackURL specified in the LinkButton) Server sends new requested page to browser. Do I really need this second roundtrip of option (2) to achieve what I want?