using System;

using System.Diagnostics;

public class Program

{

    public static void Main()

    {

        var watch = new Stopwatch();

        watch.Start();

        for (int i = 0; i < 100000000; i++)

        {

            new SealedClass().GetName();

        }

        watch.Stop();

        Console.WriteLine("Sealed class : {0}", watch.Elapsed.ToString());

        watch.Reset();

        watch.Start();

        for (int i = 0; i < 100000000; i++)

        {

            new NonSealedClass().GetName();

        }

        watch.Stop();

        Console.WriteLine("NonSealed class : {0}", watch.Elapsed.ToString());

    }

}

​

sealed class SealedClass

{

    public string GetName() => "Test";

}

​

class NonSealedClass

{

    public string GetName() => "Test";

}