问在C#中传递大字符串作为返回值的速度有多慢？

EN

static int i = 0;
static void Main(string[] args)
{
    while (Console.ReadLine() == "")
    {

        var pageSB = new StringBuilder();

        foreach (var section in new[] { AddHeader(), AddContent(), AddFooter() })
            for (int i = 0; i < section.Length; i++)
                pageSB.Append(section[i]);

        Console.Write(pageSB.ToString());
    }

}

static StringBuilder AddHeader()
{
    return new StringBuilder().Append("Hi ").AppendLine("World");
}

static StringBuilder AddContent()
{
    return new StringBuilder()
        .AppendFormat("This page has been viewed: {0} times\n", ++i);
}

static StringBuilder AddFooter()
{
    return new StringBuilder().Append("Bye ").AppendLine("World");
}