GeezerVison

using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Diagnosers;
using BenchmarkDotNet.Running;
using System;
using System.Net;
using System.Net.Http;
using System.Net.Sockets;
using System.Text;
using System.Threading.Tasks;

[MemoryDiagnoser]
public class Program
{
    static void Main(string[] args) => BenchmarkSwitcher.FromTypes(new[] { typeof(Program) }).Run(args);

    private static Socket s_listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
    private static HttpClient s_client = new HttpClient(new HttpClientHandler() { ServerCertificateCustomValidationCallback = delegate { return true; } });
    private static Uri s_uri;

    [Benchmark]
    public async Task HttpGet()
    {
        var m = new HttpRequestMessage(HttpMethod.Get, s_uri);
        m.Headers.TryAddWithoutValidation("Authorization", "ANYTHING SOMEKEY");
        m.Headers.TryAddWithoutValidation("Referer", "http://someuri.com");
        m.Headers.TryAddWithoutValidation("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/77.0.3865.90 Safari/537.36");
        m.Headers.TryAddWithoutValidation("Host", "www.somehost.com");
        (await s_client.SendAsync(m, default)).Dispose();
    }

    [GlobalSetup]
    public void CreateSocketServer()
    {
        s_listener.Bind(new IPEndPoint(IPAddress.Loopback, 0));
        s_listener.Listen(int.MaxValue);
        var ep = (IPEndPoint)s_listener.LocalEndPoint;
        s_uri = new Uri($"http://{ep.Address}:{ep.Port}/");
        byte[] response = Encoding.UTF8.GetBytes("HTTP/1.1 200 OK\r\nContent-Length: 0\r\n\r\n");
        byte[] endSequence = new byte[] { (byte)'\r', (byte)'\n', (byte)'\r', (byte)'\n' };

        Task.Run(async () =>
        {
            while (true)
            {
                Socket s = await s_listener.AcceptAsync();
                _ = Task.Run(() =>
                {
                    using (var ns = new NetworkStream(s, true))
                    {
                        byte[] buffer = new byte[1024];
                        int totalRead = 0;
                        while (true)
                        {
                            totalRead += ns.Read(buffer.AsSpan(totalRead));
                            if (buffer.AsSpan(0, totalRead).IndexOf(endSequence) == -1)
                            {
                                if (totalRead == buffer.Length) Array.Resize(ref buffer, buffer.Length * 2);
                                continue;
                            }

                            ns.Write(response);

                            totalRead = 0;
                        }
                    }
                });
            }
        });
    }
}