Everyone tests their Three.js builds on a high-end M-series Mac or a gaming rig. The real test is opening that canvas on a three-year-old budget Android phone over a patchy 4G connection. If it fails there, the implementation failed.
I’ve made it a habit to throttle my browser's CPU and simulate slow network conditions in DevTools while testing—if it’s not usable on a budget device, it’s not really 'ready' for the web.