Demonstration that async/await shouldn't cause any noticiable performance hit just because of "async/await"

gistfile1.cs

using System;
using System.Diagnostics;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            RunTest("Sync", () => DoSomeRealWork());
            RunTest("Async", () => DoSomeRealWorkAsync().Wait());

            Console.ReadLine();
        }

        static void RunTest(string desc, Action action)
        {
            var loopCount = 10;

            var globalSw = Stopwatch.StartNew();

            for (var i = 0; i < loopCount; i++)
            {
                var localSw = Stopwatch.StartNew();
                action();
                localSw.Stop();
                Console.WriteLine("{0} - Elapsed: {1} ms", desc, localSw.ElapsedMilliseconds);
            }

            globalSw.Stop();

            Console.WriteLine("{0} - Average: {1} ms", desc, globalSw.ElapsedMilliseconds / loopCount);
            Console.WriteLine();
        }

        static void DoSomeRealWork()
        {
            // do something that takes some cycles and memory alocations
            var sb = new StringBuilder();

            for (var i = 0; i < 1000000; i++)
                sb.Append("foobar");
        }

        static async Task DoSomeRealWorkAsync()
        {
            DoSomeRealWork();

            // additionally awaits 10 times for completed tasks
            for (var i = 0; i < 10; i++)
                await Task.FromResult(0);
        }
    }
}

Please note that the async version version has all the additional state machine generated code, and additionally awaits for 10 tasks.

These are the results on my machine:

Sync - Elapsed: 30 ms
Sync - Elapsed: 28 ms
Sync - Elapsed: 25 ms
Sync - Elapsed: 32 ms
Sync - Elapsed: 30 ms
Sync - Elapsed: 26 ms
Sync - Elapsed: 24 ms
Sync - Elapsed: 19 ms
Sync - Elapsed: 21 ms
Sync - Elapsed: 21 ms
Sync - Average: 26 ms

Async - Elapsed: 28 ms
Async - Elapsed: 29 ms
Async - Elapsed: 34 ms
Async - Elapsed: 26 ms
Async - Elapsed: 22 ms
Async - Elapsed: 21 ms
Async - Elapsed: 22 ms
Async - Elapsed: 23 ms
Async - Elapsed: 26 ms
Async - Elapsed: 31 ms
Async - Average: 26 ms