bench.cs

using System;
using System.Runtime.CompilerServices;
using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;

namespace MyBenchmarks
{
	public class Tests
	{
		private const int N = 10000;
		private readonly byte[] data;


		[Benchmark]
		public void Class1()
		{
			var pp = new Class1();
			pp.Foo();
		}

		[Benchmark]
		public void Class2()
		{
			var pp = new Class2();
			pp.Foo();
		}

		[Benchmark]
		public void Class2_without_callvirt()
		{
			new Class2().Foo();
		}

		[Benchmark]
		public void Class3()
		{
			IClass3 pp = new Class3();
			pp.Foo();
		}
	}

	public class Program
	{

		public static void Main(string[] args)
		{
			var summary = BenchmarkRunner.Run<Tests>();
		}
	}

	public class Class1
	{
		int a = 10;

		[MethodImpl(MethodImplOptions.NoInlining)]
		public void Foo()
		{
			a++;
		}
	}

	public class Class2
	{
		int a = 10;

		public void Foo()
		{
			a++;
		}
	}

	public interface IClass3
	{
		void Foo();
	}

	public class Class3 : IClass3
	{
		int a = 10;

		public void Foo()
		{
			a++;
		}
	}
}

/*
BenchmarkDotNet=v0.10.12, OS=Windows 10 Redstone 3 [1709, Fall Creators Update] (10.0.16299.248)
Intel Core i7-8700K CPU 3.70GHz (Coffee Lake), 1 CPU, 12 logical cores and 6 physical cores
Frequency=3609373 Hz, Resolution=277.0564 ns, Timer=TSC
  [Host]     : .NET Framework 4.7 (CLR 4.0.30319.42000), 32bit LegacyJIT-v4.7.2633.0
  DefaultJob : .NET Framework 4.7 (CLR 4.0.30319.42000), 32bit LegacyJIT-v4.7.2633.0


                  Method |     Mean |     Error |    StdDev |
------------------------ |---------:|----------:|----------:|
                  Class1 | 2.266 ns | 0.0230 ns | 0.0215 ns |
                  Class2 | 1.416 ns | 0.0452 ns | 0.0423 ns |
 Class2_without_callvirt | 1.375 ns | 0.0090 ns | 0.0080 ns |
                  Class3 | 2.534 ns | 0.0075 ns | 0.0066 ns |
*/