Необходимо пополнять какую-нибудь коллекцию парами string, int и после заполнения сортировать по убыванию int. Попробовал разные варианты в прилагаемом коде. Только сомнения в том, верно ли написал тест: код содержит OrderByDescending(pair => pair.Value, не будет ли отложенного выполнения уже после вывода результата?

using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;

namespace Сравнение_скорости_словаря_и_списка
{
  class Program
  {    
    public class myReverserClass : IComparer
    {
      int IComparer.Compare(Object x, Object y)
      {
        return ((new CaseInsensitiveComparer()).Compare(x,y ));
      }
    }
    public class myReverserClass1 : IComparer
    {
      int IComparer.Compare(object x, object y)
      {
        StrInt x1 = (StrInt)x;StrInt y1 = (StrInt)y;
        return ((new CaseInsensitiveComparer()).Compare(y1.ii,x1.ii ));
      }
    }
    class StrInt
    {
      public string str;
      public int ii;
      public StrInt(string str, int ii)
      { this.str = str; this.ii = ii; }
    }
    static void Main(string[] args)
    {
      Random rnd = new Random();
      int c1 = 10000, c2 = 50;

      Stopwatch sw = new Stopwatch();
      //1
      sw.Start();
      Dictionary<string, int>[] ardic = new Dictionary<string, int>[c1];
      for (int i = 0; i < ardic.Length; i++)
      {
        var dic = new Dictionary<string, int>(c2);
        ardic[i] = dic;
        for (int j = 0; j < c2; j++)
        {
          int value = rnd.Next();
          dic.Add(j.ToString(), value);
        }
      }
      sw.Stop(); TimeSpan tsp = new TimeSpan(); tsp += sw.Elapsed;
      Console.WriteLine(tsp);

      sw.Restart();
      Dictionary<string, int>[] ardicsort = new Dictionary<string, int>[c1];
      for (int i = 0; i < ardic.Length; i++)
      {
        ardicsort[i] = ardic[i].OrderByDescending(pair => pair.Value).ToDictionary(pair => pair.Key, pair => pair.Value);        
      }
      tsp = new TimeSpan(); tsp += sw.Elapsed;
      Console.WriteLine(tsp);

      //2
      sw.Restart();
      List<(string, int)>[] arl = new List<(string, int)>[c1];
      for (int i = 0; i < arl.Length; i++)
      {
        var l = new List<(string, int)>(c2);
        arl[i] = l;
        for (int j = 0; j < c2; j++)
        {
          int value = rnd.Next();
          l.Add((j.ToString(), value));
        }
      }
      tsp = new TimeSpan(); tsp += sw.Elapsed;
      Console.WriteLine(tsp);
      sw.Restart();
      List<(string, int)>[] arlsort = new List<(string, int)>[c1];
      for (int i = 0; i < arl.Length; i++)
      {
        arlsort[i] = arl[i].OrderByDescending(pair => pair.Item2).ToList();
      }
      tsp = new TimeSpan(); tsp += sw.Elapsed;
      Console.WriteLine(tsp);

      //3 на всякий случай проверяю не string,int а int,int
      sw.Restart();
      List< int[]>[] arlar = new List< int[]>[c1];
      for (int i = 0; i < arlar.Length; i++)
      {
        var l = new List< int[]>(c2);
        arlar[i] = l;
        for (int j = 0; j < c2; j++)
        {
          int value = rnd.Next();
          l.Add(new[] { j, value});
        }
      }
      tsp = new TimeSpan(); tsp += sw.Elapsed;
      Console.WriteLine(tsp);
      sw.Restart();
      List< int[]>[] arlarsort = new List<int[]>[c1];
      for (int i = 0; i < arlar.Length; i++)
      {
        arlarsort[i] = arlar[i].OrderByDescending(pair => pair[1]).ToList();
      }
      tsp = new TimeSpan(); tsp += sw.Elapsed;
      Console.WriteLine(tsp);

      //4
      sw.Restart();
      List<(string, int)>[] arl1 = new List<(string, int)>[c1];
      for (int i = 0; i < arl1.Length; i++)
      {
        var l = new List<(string, int)>(c2);
        arl1[i] = l;
        for (int j = 0; j < c2; j++)
        {
          int value = rnd.Next();
          l.Add((j.ToString(), value));
        }
      }
      (string, int)[][] arart = new (string, int)[arl1.Length][];
      for (int i = 0; i < arl1.Length; i++)
      { arart[i] = arl1[i].ToArray(); }
      tsp = new TimeSpan(); tsp += sw.Elapsed;
      Console.WriteLine(tsp);
      sw.Restart();
      (string, int)[][] arartsort = new (string, int)[arart.Length][];
      for (int i = 0; i < arart.Length; i++)
      {
        arartsort[i] = arl1[i].OrderByDescending(pair => pair.Item2).ToArray();       
      }
      tsp = new TimeSpan(); tsp += sw.Elapsed;
      Console.WriteLine(tsp);


      //5
      sw.Restart();
      List<StrInt>[] arlStrInt = new List<StrInt>[c1];
      for (int i = 0; i < arlStrInt.Length; i++)
      {
        var l = new List<StrInt>(c2);
        arlStrInt[i] = l;
        for (int j = 0; j < c2; j++)
        {
          int value = rnd.Next();
          l.Add(new StrInt(j.ToString(), value));
        }
      }
      StrInt[][] ararStrInt = new StrInt[arlStrInt.Length][];
      for (int i = 0; i < arlStrInt.Length; i++)
      { ararStrInt[i] = arlStrInt[i].ToArray(); }
      tsp = new TimeSpan(); tsp += sw.Elapsed;
      Console.WriteLine(tsp);
      sw.Restart();      
      IComparer myComparer1 = new myReverserClass1();
      for (int i = 0; i < ararStrInt.Length; i++)
      {       
        StrInt[] si = ararStrInt[i];
         Array.Sort(si,myComparer1);
      }
      tsp = new TimeSpan(); tsp += sw.Elapsed;
      Console.WriteLine(tsp);


      //6
      sw.Restart();
      List<string>[] arl21 = new List<string>[c1];
      List<int>[] arl22 = new List<int>[c1];
      for (int i = 0; i < arl21.Length; i++)
      {
        var l1 = new List<string>(c2); arl21[i] = l1;
        var l2 = new List<int>(c2); arl22[i] = l2;
        for (int j = 0; j < c2; j++)
        {
          int value = rnd.Next();
          l1.Add(j.ToString()); l2.Add(value);
        }
      }
      string[][] arars1 = new string[arl21.Length][];
      int[][] arari2 = new int[arl22.Length][];
      tsp = new TimeSpan(); tsp += sw.Elapsed;
      Console.WriteLine(tsp);
      sw.Restart();
      IComparer myComparer = new myReverserClass();
      for (int i = 0; i < arars1.Length; i++)
      {
        string[] ars = arl21[i].ToArray();//arars1[i]
        int[] ari = arl22[i].ToArray();//arari2[i]
        Array.Sort(ars,ari , myComparer);
        arars1[i] = ars; arari2[i] = ari;
      }
      tsp = new TimeSpan(); tsp += sw.Elapsed;
      Console.WriteLine(tsp);
      { }
    }
  }
}