Mine

using System;
using System.Collections.Generic;
using System.Text;
using System.Diagnostics;

namespace EqualsTesting
{
    class Program
    {
        static void Main(string[] args)
        {
            string one = "Hello";

            Stopwatch sw = new Stopwatch();

            sw.Start();
            for (int i = 0; i < 10000; i++)
                if (one == null || one.Length == 0)
                    Console.Write("");
            sw.Stop();

            Console.WriteLine("if (one == null || one.Length == 0) ran 10000 times in {0} ms", sw.Elapsed);

            sw.Reset();
            sw.Start();
            for (int i = 0; i < 10000; i++)
                if (one.Equals(null) || one.Equals(""))
                    Console.Write("");
            sw.Stop();

            Console.WriteLine("if (one.Equals(null) || one.Equals(\"\")) ran 10000 times in {0} ms", sw.Elapsed);

            sw.Reset();
            sw.Start();
            for (int i = 0; i < 10000; i++)
                if (string.IsNullOrEmpty(one))
                    Console.Write("");
            sw.Stop();

            Console.WriteLine("if (string.IsNullOrEmpty(one)) ran 10000 times in {0} ms", sw.Elapsed);

            Console.ReadLine();
        }
    }
}