How to make an "on the run" generator?

I want to generate a simple map while the player moves, but I don't know how to do it.I want a simple map(to be honest it is only a path made with cubes, like in the Temple Run game, but just with cubes) and only need to generate turns. I want it to destroy the blocks which is not visible.

I tried to do it with cloning the cube, but I don't think I'm doing it in the right way. At least I don't know how to make it generate turns. Because of that I didn't finished the script.

NOTE: The player moves really fast so I need a fast generator.

 using UnityEngine;
 using System.Collections;
 
 public class MapGenerator : MonoBehaviour {
 
     float minute = Time.time;
 
     public Transform tile;
     public Transform player;
 
     // Use this for initialization
     void Start () {
     
     }
     
     // Update is called once per frame
     void Update () {
         for (int x = 0; x < 100; x++)
         {
             Instantiate(tile, new Vector3(x, -6.785822f, -0.01354969f), Quaternion.identity);
         }
 
         float lastPos = 1;
         if (lastPos == player.transform.position.x)
         {
             int type = Random.Range(0, 3);
             if (type == 0)
             {
                 if (minute < 10.0f)
                 {
                     float cameraPos = player.transform.position.x;
                     for (int needToGenerateLongime = 0; needToGenerateLongime <= 6; needToGenerateLongime++)
                     {
                         Instantiate(tile, new Vector3(cameraPos + needToGenerateLongime, -6.785822f, -0.01354969f), Quaternion.identity);
                     }
                     lastPos = cameraPos + 6.0f;
                 } else if (minute)
             }
         }
     }
 }