gistfile1.cs

using System;
using System.Diagnostics;
using System.Linq;
using System.Reflection;
using System.Reflection.Emit;

namespace ilab {
    class Program {
        private delegate string StringManipulator(string input);
        static void Main(string[] args) {
            new Program();

            Console.WriteLine("Done");
            Console.ReadLine();
        }

        public Program() {
            var toLowerMethod = typeof(string).GetMethods().First(x => x.Name == "ToLower");
            var toLowerIL = GetDelegate(toLowerMethod);
            
            // Warmup
            for (var i = 0; i < 1000; i++) {
                IL(toLowerIL);
                Reflection(toLowerMethod);
            }

            var stopwatch = new Stopwatch();
            stopwatch.Start();
            for (var i = 0; i < 10000000; i++) {
                IL(toLowerIL);
            }
            stopwatch.Stop();
            Console.WriteLine("IL: {0} ms", stopwatch.ElapsedMilliseconds);
            
            stopwatch = new Stopwatch();
            stopwatch.Start();
            for (var i = 0; i < 100000; i++) {
                Reflection(toLowerMethod);
            }
            stopwatch.Stop();
            Console.WriteLine("Reflection: {0} ms", stopwatch.ElapsedMilliseconds);    
        }

        private static StringManipulator GetDelegate(MethodInfo method) {
            var dynamicMethod = new DynamicMethod("StringManipulation", typeof(string), new[] { typeof(string) }, typeof(Program).Module);
            var il = dynamicMethod.GetILGenerator();

            il.Emit(OpCodes.Ldarg_0);
            il.Emit(OpCodes.Callvirt, method);
            il.Emit(OpCodes.Ret);

            var func = dynamicMethod.CreateDelegate(typeof(StringManipulator)) as StringManipulator;
            return func;
        }

        private static void IL(StringManipulator func) {
            var result = func("aLeXAnDeR");
            Debug.Assert(result.Equals("alexander"));
        }

        private static void Reflection(MethodInfo method) {
            var result = method.Invoke("aLeXAnDeR", null);
            Debug.Assert(result.Equals("alexander"));
        }
    }
}