using System;

using System.Diagnostics;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    private static void Benchmark(Action act, int iterations)

    {

        GC.Collect();

        act.Invoke(); // run once outside of loop to avoid initialization costs

        Stopwatch sw = Stopwatch.StartNew();

        for (int i = 0; i < iterations; i++)

        {

            act.Invoke();

        }

        sw.Stop();

        Console.WriteLine((sw.ElapsedTicks).ToString().PadLeft(9, '0') + $"({sw.ElapsedMilliseconds})ms");

    }

​

    public static void Main(string[] args)

    {

        Console.WriteLine("myListToBenchmark init");

        List<int> myListToBenchmark = Enumerable.Range(0, 10000)

            .OrderBy(x => Guid.NewGuid()) //https://www.developpez.net/forums/d1827919/dotnet/langages/csharp/generation-nombres-hasard-repetition-tableau-csharp/#post10083600

            .ToList();

        Console.Write("foreach+add:  ");

        Benchmark(() => {

            List<int> outList = new();

            foreach(int v in myListToBenchmark)

                    outList.Add(v);

        }, 1000);

        Console.Write("for+add:      ");

        Benchmark(() => {

            List<int> outList = new();

            for(int i = 0; i < myListToBenchmark.Count(); i++)

                    outList.Add(myListToBenchmark[i]);

        }, 1000);

        Console.Write("addRange+where:  ");

        Benchmark(() => {

            List<int> outList = new();

            outList.AddRange(myListToBenchmark.Where(x => true));

        }, 1000);

        Console.Write("addRange+select: ");

        Benchmark(() => {

            List<int> outList = new();

            outList.AddRange(myListToBenchmark.Select(i => i));

        }, 1000);

        Console.Write("addRange:        ");

        Benchmark(() => {

            List<int> outList = new();

            outList.AddRange(myListToBenchmark);

        }, 1000);

    }

}