using System;

using System.Diagnostics;

​

public class Program

{

    public static void Main()

    {

        Foo f = new Foo();

        IFoo f2 = f;

        // JIT warm-up

        for (int i = 0; i < 10; i++)

        {

            f.Bar();

            f2.Bar();

        }

​

        int N = 10000000;

        Stopwatch sw = new Stopwatch();

        sw.Start();

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

        {

            f.Bar();

        }

​

        sw.Stop();

        Console.WriteLine("Direct call: {0:F2}", sw.Elapsed.TotalMilliseconds);

        sw.Reset();

        sw.Start();

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

        {

            f2.Bar();

        }

​

        sw.Stop();

        Console.WriteLine("Through interface: {0:F2}", sw.Elapsed.TotalMilliseconds);

    // Results:

    // Direct call:       23,28

    // Through interface: 38,68

    }

}

​

interface IFoo

{

    void Bar();

}

​

class Foo : IFoo

{

    public virtual void Bar()

    {

    }

}