stats.js shows FPS 0~2, render movement too slow - vue.js

Question

i'm beginner for three.js also using it for BIM project,
when i load a gltf file of ~25mb i can barely move the whole object and stats.js monitor shows fps of 0~2 at max
gltf file : https://github.com/xeolabs/xeogl/tree/master/examples/models/gltf/schependomlaan
im using THREE js with vuejs
//package.json
"stats.js": "^0.17.0",
"three": "^0.109.0",
import * as THREE from 'three';
import { GLTFLoader } from 'three/examples/jsm/loaders/GLTFLoader.js';
import { DRACOLoader } from 'three/examples/jsm/loaders/DRACOLoader.js';
import { OrbitControls } from 'three/examples/jsm/controls/OrbitControls.js';
this.scene = new THREE.Scene();
this.stats = new Stats();
this.stats.showPanel( 0, 1, 2 ); // 0: fps, 1: ms, 2: mb, 3+: custom
let div = document.createElement('div')
div.appendChild(this.stats.dom)
div.style.position = 'absolute';
div.style.top = 0;
div.style.left = 0;
document.getElementsByClassName('gltfViewer')[0].appendChild( div );
// Camera
this.camera = new THREE.PerspectiveCamera( 45, window.innerWidth / window.innerHeight, 1, 1500 );
this.camera.position.set( this.pos, this.pos, this.pos );
// renderer
this.raycaster = new THREE.Raycaster();
this.renderer = new THREE.WebGLRenderer({ canvas: document.getElementById('gltfViewerCanvas'), alpha: false });
this.renderer.setClearColor( 0xefefef );
this.renderer.setPixelRatio( window.devicePixelRatio );
this.renderer.setSize(window.innerWidth, window.innerHeight);
// adding controls
this.controls = new OrbitControls( this.camera, this.renderer.domElement );
this.controls.dampingFactor = 0.1;
this.controls.rotateSpeed = 0.12;
this.controls.enableDamping = true;
this.controls.update();
window.addEventListener('resize', _ => this.render());
this.controls.addEventListener('change', _ => this.render());
// light
var ambientLight = new THREE.AmbientLight( 0xcccccc );
this.scene.add( ambientLight );
var directionalLight = new THREE.DirectionalLight( 0xffffff );
directionalLight.position.set( 0, 1, 1 ).normalize();
this.scene.add( directionalLight );
// loading gltf file
// Instantiate a loader
this.gltfLoader = new GLTFLoader();
// Optional: Provide a DRACOLoader instance to decode compressed mesh data
this.dracoLoader = new DRACOLoader();
this.dracoLoader.setDecoderPath( 'three/examples/js/libs/draco' );
this.gltfLoader.setDRACOLoader( this.dracoLoader );
// Load a glTF resource
this.gltfLoader.load( this.src, this.onGLTFLoaded, this.onGLTFLoading, this.onGLTFLoadingError );
//onGLTFLoaded()
this.scene.add( optimizedGltf.scene );
// gltf.scene.getObjectById(404).visible = false;
this.listGltfObjects(gltf);
this.render();
// render ()
this.renderer.render( this.scene, this.camera );
this.stats.update();
// on mounted component :
animate()
// animate()
this.stats.begin()
this.render();
this.stats.end();
even after applying Draco compression using https://github.com/AnalyticalGraphicsInc/gltf-pipeline nothing changes.
Thanks

Answer 1

On filesize —
Draco compression reduces network size, but not the final amount of uncompressed data that must be sent to your GPU and rendered. If your original mesh was 100mb and you compress it to 25mb, you will still get the framerate of the original 100mb mesh. Aside: Using the -b option of glTF-Pipeline will reduce the size by another 50%, to 13MB, but again doesn't affect FPS.
On framerate —
This model contains 4280 meshes1, each requiring a GPU draw call. That is the source of your low QPS, and unfortunately it's a common problem in BIM models. You'll need to merge these meshes (in a program like Blender, or after loading in three.js) to as few as possible. A model like this should require < 100 draw calls, or even as few as 1.
1 To see this, try opening the model on https://gltf-viewer.donmccurdy.com/ and opening the JavaScript console. You should see a printout of the scene graph, which will contain many different meshes.