Lazy Loading

Third-party scripts are a common cause of poor Core Web Vitals. This post ranks five lazy-loading techniques by their practical impact on page speed.

A common refrain is that React Router lazy loading is just about swapping import for lazy. That framing leaves out the loading states, the error boundaries, and the bundle-size math that decides whether the technique helps at all.

Lazy loading with Intersection Observer is straightforward in theory, but several common implementation mistakes silently break it. Here is a symptom-based checklist to diagnose and fix them.