Why is Unity freezing with this code?

I have clones of a cube at every position in a box of 10x10x10 with a step of 0.25 (40 cubes in the x direction, 40 cubes in the y direction, and 40 cubes in the z direction). I am trying to change the transparency of the cubes based on a text file, which has 64000 lines (with the first column corresponding to x values, the second column to y values, the third column to z values, and the fourth column to transparency values). I put this script on the cube, which is then cloned, so every cube has that script attached to it.

 using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
 using UnityEngine;
 using System.IO;
 using System;
 using System.Runtime.InteropServices;
 using System.Security.Cryptography;
 
 public class FileManager : MonoBehaviour
 {
     public Renderer rend;
     public Color color;
     string filePath, fileName;
 
     void Update()
     {
         if (Input.GetKeyDown("space"))
         {
             StartCoroutine(Delay());
         }
     }
 
     void LateUpdate()
     {
         Color color = this.GetComponent<MeshRenderer>().material.color;
         rend = GetComponent<Renderer>();
         if (color.a == 0)
         {
             rend.enabled = false;
         }
     }
 
     public IEnumerator Delay()
     {
         for (int i = 3; i <= 3; i++)
         {
             rend.enabled = false;
             fileName = "Wave_Time_" + i + ".txt";
             filePath = Application.dataPath + "/" + fileName;
             ReadFromTheFile();
             yield return null;
         }
     }
 
     public class Point
     {
         public float x { get; set; }
         public float y { get; set; }
         public float z { get; set; }
         public float p { get; set; }
     }
 
     public void ReadFromTheFile()
     {
         List<Point> Points = new List<Point>();
         List<string> lines = File.ReadAllLines(filePath).ToList();
         foreach (var line in lines)
         {
             string[] entries = line.Split(',');
 
             Point newPoint = new Point();
 
             newPoint.x = float.Parse(entries[0]);
             newPoint.y = float.Parse(entries[1]);
             newPoint.z = float.Parse(entries[2]);
             newPoint.p = float.Parse(entries[3]);
 
             Points.Add(newPoint);
         }
 
         Color color = this.GetComponent<MeshRenderer>().material.color;
         rend = GetComponent<Renderer>();
         float index = (4 * transform.position.x) * 1600 + (4 * transform.position.y) * 40 + (4 * transform.position.z);
         color.a = Points[(int) index].p;
         this.GetComponent<MeshRenderer>().material.color = color;
     }
 }