I'm encountering performance issues where the requestAnimationFrame handler takes ms during the loading of a large GLB file in my Three.js setup.

Below is the code that sets up the scene, loads the model, and runs the animation loop. I've already considered several optimization strategies such as:

1. Using Level of Detail (LOD) to swap models based on camera distance.
2. Employing instanced meshes for rendering many identical objects.
3. Optimizing geometry by reducing the polygon count.
4. Loading models asynchronously in smaller parts.
5. Utilizing Draco compression to reduce file size.

I'm looking for advice on which of these techniques might be most effective or if there are other best practices to reduce these delays. Any guidance would be appreciated.

TYPESCRIPTCopied
import * as THREE from 'three';
import { GLTFLoader } from 'three/examples/jsm/loaders/GLTFLoader.js';
import { OrbitControls } from 'three/examples/jsm/controls/OrbitControls.js';
import Stats from 'three/examples/jsm/libs/stats.module.js';

export class Main {
    private scene: THREE.Scene;
    private camera: THREE.PerspectiveCamera;
    private renderer: THREE.WebGLRenderer;
    private controls: OrbitControls;
    private stats: Stats;

    constructor() {
        // Create scene
        this.scene = new THREE.Scene();
        this.scene.background = new THREE.Color(0xf0f0f0);

        // Create camera
        this.camera = new THREE.PerspectiveCamera(
            75,
            window.innerWidth / window.innerHeight,
            0.1,
            10000
        );
        this.camera.position.set(0, 5, 10);

        // Create renderer
        this.renderer = new THREE.WebGLRenderer({ antialias: true });
        this.renderer.setSize(window.innerWidth, window.innerHeight);
        this.renderer.setPixelRatio(window.devicePixelRatio);
        this.renderer.shadowMap.enabled = true;
        document.body.appendChild(this.renderer.domElement);

        // Create stats
        this.stats = new Stats();
        document.body.appendChild(this.stats.dom);

        // Add controls
        this.controls = new OrbitControls(this.camera, this.renderer.domElement);
        this.controls.enableDamping = true;
        this.controls.dampingFactor = 0.05;

        // Add lights
        const ambientLight = new THREE.AmbientLight(0xffffff, 0.5);
        this.scene.add(ambientLight);

        const directionalLight = new THREE.DirectionalLight(0xffffff, 1);
        directionalLight.position.set(5, 5, 5);
        directionalLight.castShadow = true;
        this.scene.add(directionalLight);

        // Load GLB
        this.loadModel();

        // Handle window resize
        window.addEventListener('resize', this.onWindowResize.bind(this));

        // Start animation loop
        this.animate();
    }

    // Load the model
    private loadModel(): void {
        const loader = new GLTFLoader();
        const url = 'path/to/my/file.glb';

        loader.load(
            url,
            (gltf) => {
                const model = gltf.scene;
                
                // Center the model
                const box = new THREE.Box3().setFromObject(model);
                const center = box.getCenter(new THREE.Vector3());
                model.position.sub(center);
                
                this.scene.add(model);
                
                // Adjust camera to fit model
                const size = box.getSize(new THREE.Vector3());
                const maxDim = Math.max(size.x, size.y, size.z);
                const fov = this.camera.fov * (Math.PI / 180);
                let cameraZ = Math.abs(maxDim / 2 / Math.tan(fov / 2));
                this.camera.position.z = cameraZ * 1.5;
                
                this.camera.updateProjectionMatrix();
                this.controls.target.set(0, 0, 0);
                this.controls.update();
            },
            (progress) => {
                console.log(`Loading: ${(progress.loaded / progress.total * 100)}%`);
            },
            (error) => {
                console.error('Error loading model:', error);
            }
        );
    }

    private onWindowResize(): void {
        // Update camera
        this.camera.aspect = window.innerWidth / window.innerHeight;
        this.camera.updateProjectionMatrix();

        // Update renderer
        this.renderer.setSize(window.innerWidth, window.innerHeight);
    }

    private animate(): void {
        requestAnimationFrame(() => this.animate());
        
        // Update controls
        this.controls.update();
        this.stats.update();
        // Render scene
        this.renderer.render(this.scene, this.camera);
    }
}

// Initialize the application
new Main();