Default.aspx loads slow without page name in url

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C#

DevExpress

website

ASP.NET4

Hi all,
I'm developing a asp.net c# web application.
Basically, my login page is default.aspx, which is in root of the application.
I've set to run in iis, where the url will be http://127.0.0.1/WebSite1

My problem is if i run from any web browser with the url http://127.0.0.1/WebSite1/ my web application takes some time to load the default.aspx (which is the login page). It takes about 1-3 minutes to load the default.aspx page.

But, if i run with the url http://127.0.0.1/WebSite1/default.aspx, it loads fast without any issue.

Even if i run from my visual studio still getting the same issue.

What I have tried:

I've tried below on web.config ;
Attempt 1:

<authentication mode="Forms">
      <forms name=".ASPXAUTH" loginUrl="/default.aspx" />
    </authentication>
      <authorization>
        <deny users="?"/>
      </authorization>

Attempt 2:

<location path="default.aspx">
    <system.web>
      <authorization>
        <allow users="*" />
      </authorization>
    </system.web>
  </location>

On my default.aspx.cs ;

protected void Page_Load(object sender, EventArgs e)
    {
if (Request.IsAuthenticated)
        {
            Response.Redirect("~/Main.aspx");
        }
}

Anything i missed here?