Script variable can be referenced in Start but not in update.

Hello, I have a two part question. First, I can print a gameObjects speed fine in the method where it was initialized, but when I follow the exact same process inside update it prints 0. Why would this be?

Secondly I was told that it's a bad idea to be calling getObjects() for the stats script every frame because it was an expensive operation and that I should instead look into making a global variable for the scripts. The problem I have with this is that I sort the gameobjects by speed every single turn, so the scripts location might not be easy to access. I thought about storing the script with the gameObject in a "pair" but I don't think that that is the right solution either.

 public PlayerStats playerStats;
 List<GameObject> players = new List<GameObject>();
 
 void Start()
     {
         //create players
         GameObject player1 = GameObject.CreatePrimitive(PrimitiveType.Capsule);
         player1.transform.position = new Vector3(4,1,0);
         PlayerStats player1Stats = player1.AddComponent<PlayerStats>();
         player1.tag = "Player";
         player1Stats.setSpeed (15.0f);
         print(player1Stats.speed);
                 //This line prints 15, as expected
         
         GameObject player2 = GameObject.CreatePrimitive(PrimitiveType.Capsule);
         player2.transform.position = new Vector3(0,1,4);
         PlayerStats player2Stats = player2.AddComponent<PlayerStats>();
         player2.tag = "Player";
         player2Stats.setSpeed (10.0f);
         print(player2Stats.speed);
                 //this line prints 10, as expected
         
         players.Add(player1);
         players.Add(player2);
         
         PlayerStats ps;
         ps = players[0].GetComponent<PlayerStats>();
         print(ps.speed);
                 //this line prints 15, as expected
                 
     }
 
     // Update is called once per frame
     void Update () {        
         int playerSize = players.Count;
         int index = 0;
         PlayerStats ps;
         
         while(index < playerSize)
         {
             ps = players[index].GetComponent<PlayerStats>();
             print(ps.speed);
                         //this line ALWAYS prints 0, when it should print either 10 or                  
                         //15.
             index++;
         }