In today's world of web development, delivering a seamless and efficient user experience is critical. Google Core Web Vitals has emerged as a crucial set of metrics to assess and optimize websites. In this article, we'll delve into what Core Web Vitals are, why they matter, and provide simple ways to enhance them for your Next.js project.

Understanding Google Core Web Vitals

Core Web Vitals can be broken down into three main aspects

• Largest Contentful Paint (LCP)
• First Input Delay (FID)
• Cumulative Layout Shift (CLS)

Largest Contentful Paint (LCP)

LCP measures the time it takes for the main content of a page to load. It should ideally occur within 2.5 seconds of when the page first starts loading.

Major Causes of Poor LCP

How can we improve LCP in Nextjs

• Optimize images using next/image tag.
• Utilize lazy loading for images.
• Add experimental: { optimizeCss: true } in next config to generate critical css (experimental feature).

First Input Delay (FID)

FID quantifies the responsiveness of a web page by measuring the time it takes for a user to interact with it. An ideal FID is less than 100 milliseconds.

How we can improve FID in Nextjs

• Make use of @next/bundle-analyzer to analyse bundle sizes.
• Use next/dynamic tag to implement lazy loading imports of React components where necessary.
• Utilize next/script tag to optimally load third-party scripts

Cumulative Layout Shift (CLS)

CLS assesses the visual stability of a page by measuring unexpected layout shifts during its lifespan. A good CLS score is less than 0.1.

How we can improve CLS in Nextjs

• Take advantage of next/font to automatically optimize your fonts (including custom fonts) and remove external network requests for improved privacy and performance.
• Add fixed dimensions to next/image tag images.

Conclusion:

By prioritizing Google Core Web Vitals, you can significantly enhance the user experience of your Next.js project. Optimizing for LCP, FID, and CLS ensures that your website is not only search engine-friendly but also provides a seamless experience for your users. Incorporate these simple strategies into your development workflow to create faster, more responsive, and visually stable web applications.

Resources

*https://www.youtube.com/watch?v=AQqFZ5t8uNc&t=137s