Obs vs event perf tests

gistfile1.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reactive.Subjects;
using System.Text;
using System.Threading.Tasks;
using System.Reactive.Linq;
using Stacks;
using System.Threading;
using System.Diagnostics;

namespace ConsoleApplication23
{
    class Foo
    {
        public event Action<int> FooEvent;
        public event Action<int> FooEventExec;

        private Subject<int> fooSub;
        private Subject<int> fooSubExec;
        public IObservable<int> FooObs { get { return fooSub.AsObservable(); } }
        public IObservable<int> FooObsExec { get { return fooSubExec.ObserveOn(exec); } }

        private ActionBlockExecutor exec;

        public Foo()
        {
            fooSub = new Subject<int>();
            fooSubExec = new Subject<int>();

            exec = new ActionBlockExecutor();
        }

        public void RunEvents(int count)
        {
            for (int i = 0; i < count; ++i)
            {
                var h = FooEvent;
                if (h != null)
                    h(i);
            }
        }

        public void RunObs(int count)
        {
            for (int i = 0; i < count; ++i)
            {
                fooSub.OnNext(i);
            }
        }

        public void RunEventsExec(int count)
        {
            for (int i = 0; i < count; ++i)
            {
                var h = FooEventExec;
                int j = i;
                if (h != null)
                    exec.Enqueue(() => h(j));
            }
        }

        public void RunObsExec(int count)
        {
            for (int i = 0; i < count; ++i)
            {
                fooSubExec.OnNext(i);
            }
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            int count = 100000;
            long expectedSum = (long)count * ((long)count - 1L) / 2L;
            Foo f = new Foo();
            long evSum = 0, obsSum = 0;
            long evESum = 0, obsESum = 0;

            f.FooEvent += i => { evSum += i; };
            f.FooEventExec += i => { evESum += i; };
            f.FooObs.Subscribe(i => { obsSum += i; });
            f.FooObsExec.Subscribe(i => { obsESum += i; });

            var sw = Stopwatch.StartNew();
            f.RunEvents(count);
            sw.Stop();
            Console.WriteLine("Events: " + sw.ElapsedMilliseconds + " ms");

            sw.Restart();
            f.RunObs(count);
            sw.Stop();
            Console.WriteLine("Obs: " + sw.ElapsedMilliseconds + " ms");

            sw.Restart();
            f.RunEventsExec(count);
            while (Volatile.Read(ref evESum) != expectedSum) Thread.Yield();            
            sw.Stop();
            Console.WriteLine("Events (executor): " + sw.ElapsedMilliseconds + " ms");

            sw.Restart();
            f.RunObsExec(count);
            while (Volatile.Read(ref obsESum) != expectedSum) Thread.Yield();            
            sw.Stop();
            Console.WriteLine("Obs (executor): " + sw.ElapsedMilliseconds + " ms");

            Console.WriteLine(evSum);
            Console.WriteLine(evESum);
            Console.WriteLine(obsSum);
            Console.WriteLine(obsESum);

            Console.ReadKey();
        }
    }
}