using System;

using System.Collections.Generic;

using System.Linq;

using System.Diagnostics;

public class Program

{

    public static void Main()

    {

        List<int> list = Enumerable.Range(0,500000).Select(x => x).ToList();

        Stopwatch stopWatch = new Stopwatch();

        stopWatch.Start();

        var a = list.Where(x => x%2 == 0).GroupBy(y => y);

        stopWatch.Stop();

        TimeSpan aTime = stopWatch.Elapsed;

        stopWatch.Reset();

        stopWatch.Start();

        var b = list.FindAll(x => x%2 == 0).GroupBy(y => y);

        stopWatch.Stop();

        TimeSpan bTime = stopWatch.Elapsed;

        Console.WriteLine("Enumerable.Where ms: " + aTime.Milliseconds);

        Console.WriteLine("List.Findall ms: " + bTime.Milliseconds);

    }

}