Use aspx.cs code in aspx page

Question

I have a Doubt that what effect will occure if use the aspx.cs page code in .aspx page.
Like:

<form id="form1" runat="server">
    <div> 
 <script runat="server">
            protected void Page_Load(object sender, EventArgs e)
            {
                 Response.Write("aspx");
            }
        </script>
</div>
</form>

Can it effect the performance of Application if yes( How???).
Please Clear my Doubt...