using System;

using System.Diagnostics;

public class Program

{

    private static void Benchmark(Action act, int iterations)

    {

        GC.Collect();

        act.Invoke(); // run once outside of loop to avoid initialization costs

        Stopwatch sw = Stopwatch.StartNew();

        for (int i = 0; i < iterations; i++)

        {

            act.Invoke();

        }

        sw.Stop();

        Console.WriteLine((sw.ElapsedTicks).ToString());

    }

​

    public static void Main(string[] args)

    {

        var someString = "HelloWorld!";

        var emptyString = "";

        Benchmark(() => { var test = (someString == ""); }, 100000);

        Benchmark(() => { var test = (someString.Length == 0); }, 100000);

        Benchmark(() => { var test = (String.IsNullOrEmpty(someString)); }, 100000);

        Benchmark(() => { var test = (emptyString == ""); }, 100000);

        Benchmark(() => { var test = (emptyString.Length == 0); }, 100000);

        Benchmark(() => { var test = (String.IsNullOrEmpty(emptyString)); }, 100000);

    }

}