using System;

using System.Diagnostics;

using System.Threading;

using System.Threading.Tasks;

public class Program

{

    public static void Main()

    {

        var sw = Stopwatch.StartNew();

        var f1 = Foo("f1");

        var f2 = Foo("f2");

        Task.WhenAll(f1,f2).Wait();

        Console.WriteLine($"2 таски * 5 циклов * 250мс на цикл = {sw.ElapsedMilliseconds}мс");

        sw = Stopwatch.StartNew();

        var b1 = Bar("b1");

        var b2 = Bar("b2");

        Task.WhenAll(b1,b2).Wait();

        Console.WriteLine($"2 таски * 5 циклов * 250мс на цикл = {sw.ElapsedMilliseconds}мс");

    }

​

​

    static async Task Foo(string id){

        for(int i=0; i< 5; i++){

            await Task.Delay(250);

            (id + ". Thread:" + Thread.CurrentThread.ManagedThreadId).Dump();

        }

    }

​

    static Task Bar(string id){

        for(int i=0; i< 5; i++){

            Thread.Sleep(250);

            (id + ". Thread:" + Thread.CurrentThread.ManagedThreadId).Dump();

        }

        return Task.CompletedTask;

    }

}