Asp.net viewstate’leri footera taşımak isterseniz masterpage kod kısmına aşağıdaki kodu eklemeniz yeterlidir.

protected override void Render(System.Web.UI.HtmlTextWriter writer)
{
System.IO.StringWriter stringWriter = new System.IO.StringWriter();
HtmlTextWriter htmlWriter = new HtmlTextWriter(stringWriter);
base.Render(htmlWriter);
string html = stringWriter.ToString();
int StartPoint = html.IndexOf("<input type=\"hidden\" name=\"__VIEWSTATE\"");
if (StartPoint >= 0)
{
int EndPoint = html.IndexOf("/>", StartPoint) + 2;
string viewstateInput = html.Substring(StartPoint, EndPoint - StartPoint);
html = html.Remove(StartPoint, EndPoint - StartPoint);
int FormEndStart = html.IndexOf("</form>");
if (FormEndStart > 0)
{
html = html.Insert(FormEndStart, viewstateInput);
}
}
writer.Write(html);
}

Eğerki hem hem viewstateleri footer indirme hemde boşlukları silmek isterseniz aşağıdaki kodları kullanabilirsiniz.

private static readonly Regex REGEX_BETWEEN_TAGS = new Regex(@">\s+<", RegexOptions.Compiled);
    private static readonly Regex REGEX_LINE_BREAKS = new Regex(@"\n\s+", RegexOptions.Compiled);

    protected override void Render(HtmlTextWriter writer)
    {
        using (HtmlTextWriter htmlwriter = new HtmlTextWriter(new System.IO.StringWriter()))
        {
            base.Render(htmlwriter);
            string html = htmlwriter.InnerWriter.ToString();

            html = REGEX_BETWEEN_TAGS.Replace(html, "> <");
            html = REGEX_LINE_BREAKS.Replace(html, string.Empty);

           // html = html.Trim().Replace("<form", "<div");
            html = html.Trim();
            int StartPoint = html.IndexOf("<input type=\"hidden\" name=\"__VIEWSTATE\"");
            if (StartPoint >= 0)
            {
                int EndPoint = html.IndexOf("/>", StartPoint) + 2;
                string viewstateInput = html.Substring(StartPoint, EndPoint - StartPoint);
                html = html.Remove(StartPoint, EndPoint - StartPoint);
                int FormEndStart = html.IndexOf("</form>");
                if (FormEndStart > 0)
                {
                    html = html.Insert(FormEndStart, viewstateInput);
                }
            }
            writer.Write(html);


           
        }
    }