Optimizing Core Web Vitals in Next.js: Tips and Tricks for Improved Performance

As web applications continue to grow in complexity and size, optimizing their performance has become more crucial than ever. With the introduction of Core Web Vitals, it has become essential to optimize your Next.js application to provide a great user experience. In this article, we will explore some of the ways to improve the Core Web Vitals of a Next.js application.

What are Core Web Vitals? Core Web Vitals are a set of metrics introduced by Google to measure the user experience on a website. They are designed to measure the loading speed, interactivity, and visual stability of a website. The three core web vitals are:

1. Largest Contentful Paint (LCP): measures loading performance. It reports the render time of the largest element visible in the viewport.
2. First Input Delay (FID): measures interactivity. It reports the time it takes for a user to interact with the website for the first time.
3. Cumulative Layout Shift (CLS): measures visual stability. It reports the amount of unexpected layout shift during the loading process.

Improving Core Web Vitals in Next.js

Optimize Images:

One of the main culprits for slow LCP is large image sizes. In Next.js, you can use the “next/image” component to optimize your images. The component automatically resizes and compresses images to reduce their size.

Here’s an example of using the “next/image” component:

import Image from 'next/image'
function MyComponent() {
  return (
    <div>
      <Image
        src="/my-image.jpg"
        alt="My Image"
        width={500}
        height={500}
      />
    </div>
  )
}

Code Splitting:

Next.js has built-in support for code splitting, which can significantly improve the loading performance of your application. Code splitting allows you to split your code into smaller chunks, which can be loaded on demand. This reduces the amount of code that needs to be loaded upfront, improving the loading performance of your application.