Unity C# Procedural World Generation Cant Handle Big Maps

so, I'm making a terraria-like game in unity using c# which has procedurally generated tilemaps and i have this script attached to a grid:

using UnityEngine;
using AccidentalNoise;
using System.Collections.Generic;
using UnityEngine.Tilemaps;
using System;

public class CompileTerrain : MonoBehaviour
{

    public TileBase dirtTile;
    public TileBase grassTile;
    public TileBase stoneTile;

    public List<GameObject> fractalLayers = new List<GameObject>();

    public Tilemap grid;
    public int width;
    public int height;

    public float seed;
    public int caveSmoothness = 2;

    void Start()
    {
        grid.ClearAllTiles();

        int touchCount = 0;
        Vector3Int newPos;
        double nx, ny;

        ModuleBase combinedTerrain = CavesAndMountains((uint)seed);
        List<Vector3Int> terrainCoords = new List<Vector3Int>();
        SMappingRanges ranges = new SMappingRanges();

        for (int x …