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# Next.js Unleashed: Optimizing Web Vitals for superior User Experience

Why manually wrestle with asset delivery to fix poor Core Web Vitals? See how four built-in Next.js components effortlessly boost your sluggish React app to a perfect Lighthouse score.

- **Speakers:** [Eileen Fürstenau](https://www.wearedevelopers.com/@eileen-furstenau)
- **Event:** World Congress 2024
- **Published:** August 20, 2024
- **Duration:** 26:44
- **URL:** https://www.wearedevelopers.com/videos/973-next-js-unleashed-optimizing-web-vitals-for-superior-user-experience

## Summary

A side project meant to solve a fun real-world problem—indecisively ordering wine—turns into a practical lesson on web performance when its initial Lighthouse score sinks. This journey illustrates the importance of Core Web Vitals, a set of metrics spearheaded by Google that measure loading performance, visual stability, and interactivity to accurately evaluate overall user experience and SEO consequences.

The solution to these performance bottlenecks lies in leveraging Next.js. As modern React development shifts toward relying on full-fledged frameworks rather than standalone setups, Next.js stands out by providing built-in server-side rendering (SSR) and a robust suite of out-of-the-box optimization tools. Rather than manually wrestling with asset delivery, developers can effortlessly plug in specific Next.js components to dramatically boost crucial performance metrics like Largest Contentful Paint (LCP), Cumulative Layout Shift (CLS), and Interaction to Next Paint (INP).

The practical application focuses on four key Next.js features that require minimal manual effort but deliver massive optimization results. Implementing the `next/image` component automatically handles resizing and modern image formatting (like WebP) to eliminate unexpected layout shifts. Relying on Next.js font optimization self-hosts external Google fonts and inlines CSS at build time, successfully neutralizing render-blocking network requests. Furthermore, executing dynamic ESM imports to lazy-load heavy third-party search libraries and hidden React components drastically slims down the initial JavaScript payload. Finally, controlling the execution timing of external analytics with `next/script` ensures that main-thread resources are never blocked by third-party tracking. Together, these straightforward modifications turn sluggish applications into highly performant experiences capable of achieving a perfect 100 Lighthouse score.

**Keywords:** next.js performance, core web vitals, lighthouse performance score, next/image, largest contentful paint (lcp), cumulative layout shift (cls), interaction to next paint (inp), server-side rendering (ssr), next/font, dynamic imports, javascript payload reduction, lazy loading react components, next/script, third-party script management, render-blocking resources, search engine optimization (seo)

## Chapters

1. **Building a personal app and discovering poor performance** (00:03) — Constructing a simple application reveals unexpected front-end performance bottlenecks measured by a low Lighthouse baseline score.
1. **Understanding the business impact of web vitals** (03:48) — Poor website performance negatively impacts overall user experience, customer satisfaction, and search engine optimization rankings.
1. **Exploring core web vitals and user experience metrics** (05:58) — Core web vitals evaluate site health by strictly measuring loading speed, visual stability, and interactive delays.
1. **Leveraging the Next.js framework for performance improvements** (08:09) — Next.js provides built-in server-side rendering and static site generation to effectively overcome standard single-page application bottlenecks.
1. **Optimizing images for stable layouts and visual performance** (11:15) — Replacing standard HTML image tags with the Next.js image component automatically enables responsive resizing and modern formats like WebP.
1. **Preventing render blocking and layout shifts with fonts** (14:36) — Inlining font styles at build time and self-hosting external typefaces prevents extra network requests and eliminates raw text flickering.
1. **Reducing initial bundle size via dynamic component imports** (18:10) — Deferring the loading of heavy third-party libraries and hidden UI elements drastically decreases initial JavaScript execution time.
1. **Managing third-party script execution and loading strategies** (22:39) — Utilizing customized component strategies prevents external analytics scripts from blocking critical page rendering resources.
1. **Achieving a perfect performance score with native features** (24:31) — Implementing simple framework-specific optimizations dramatically improves overall metrics and ensures seamless user experiences across devices.

## Related Moments

- [Internal performance optimizations and Tailwind CSS integration](https://www.wearedevelopers.com/videos/985-beyond-warp-speed-crafting-the-future-of-web-development-with-astro-4-10) (from "Beyond Warp Speed: Crafting the Future of Web Development with Astro 4.10")
- [Applying quick performance wins to personal websites](https://www.wearedevelopers.com/videos/903-catching-up-on-the-basics-you-don-t-really-need-that-much-code) (from "Catching up on the basics you don't really need that much code")
- [Reviewing optimization improvements in Lighthouse](https://www.wearedevelopers.com/videos/453-is-your-progressive-web-app-lazy-how-to-read-and-improve-your-pwa-performance) (from "Is your Progressive Web App Lazy? How to read and improve your PWA Performance")
- [Architecture and performance optimizations in React Native](https://www.wearedevelopers.com/videos/1466-building-better-apps-with-react-native) (from "Building Better Apps with React Native")
- [Modernizing legacy client-rendered components with server-side frameworks](https://www.wearedevelopers.com/videos/1587-web-fragments-incremental-micro-frontends-migration-approach-for-enterprise) (from "Web-Fragments: incremental micro-frontends migration approach for enterprise")
- [Scaffolding pages and routing single-page applications with Next.js](https://www.wearedevelopers.com/videos/311-graphql-apollo-next-js-a-lovely-trio) (from "GraphQL + Apollo + Next.js: A Lovely Trio")

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