Speed up website

Page load - CDN(static content or media), caching -  Cache page content, queries, expensive computation   
DB - connection pooling, distributed caching, in-memory db
profiler
reduce IO
load balancer and multiple servers
async processing and scheduling processes
compress pages and response

tools to benchmark and load test
soapUI
Fiddler
YSlow
JMeter

Get Windows credentials from C# application

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Principal;

namespace ConsoleApplication1
{
    class Program
    {
        static string loggedInUser;
        static string userLocalGroup = null;
        static string usersGroupSIDs = null;
        static string currentUserDetails;

        static void Main(string[] args)
        {

            loggedInUser = WindowsIdentity.GetCurrent().Name;
            WindowsPrincipal principal = new WindowsPrincipal(WindowsIdentity.GetCurrent());


            IdentityReferenceCollection irc = WindowsIdentity.GetCurrent().Groups;
            foreach (IdentityReference ir in irc)
            {
                usersGroupSIDs = usersGroupSIDs + " , " + ir.Value.ToString();
            }
            if (principal.IsInRole(WindowsBuiltInRole.Administrator))
                userLocalGroup = userLocalGroup + " Adminstrator ,";
            if (principal.IsInRole(WindowsBuiltInRole.AccountOperator))
                userLocalGroup = userLocalGroup + " AccountOperator ,";
            if (principal.IsInRole(WindowsBuiltInRole.BackupOperator))
                userLocalGroup = userLocalGroup + " BackupOperator ,";
            if (principal.IsInRole(WindowsBuiltInRole.Guest))
                userLocalGroup = userLocalGroup + " Guest ,";
            if (principal.IsInRole(WindowsBuiltInRole.PowerUser))
                userLocalGroup = userLocalGroup + " PowerUser";
            if (principal.IsInRole(WindowsBuiltInRole.PrintOperator))
                userLocalGroup = userLocalGroup + "PrintOperator ,";
            if (principal.IsInRole(WindowsBuiltInRole.Replicator))
                userLocalGroup = userLocalGroup + " Replicator ,";
            if (principal.IsInRole(WindowsBuiltInRole.SystemOperator))
                userLocalGroup = userLocalGroup + " SystemOperator ,";
            if (principal.IsInRole(WindowsBuiltInRole.User))
                userLocalGroup = userLocalGroup + " User";

            // }
            currentUserDetails = WindowsIdentity.GetCurrent().ToString();

            Console.WriteLine("Logged in user : " + loggedInUser);
            Console.WriteLine("Logged in user belongs to Local Groups : " + userLocalGroup);

            Console.WriteLine("Logged in user belongs to SID Groups : " + usersGroupSIDs);
            Console.WriteLine("Current user Object is  : " + currentUserDetails);
        }
    }
}

Bank of America–error page