Optimizing Next.js Performance: Lighthouse Audits, Caching, and Beyond

When it comes to ensuring optimal application experience, performance optimization plays a crucial role. For applications build with Next.js, this process can be enhanced through several strategies, with the implementation of Lighthouse audits being a preferred choice.

The Role of Lighthouse Audits in Performance Optimization

Lighthouse, an open-source tool developed by Google, powers audits for web pages. It offers a comprehensive performance scoring system that helps in evaluating the speed and efficiency of a website. Lighthouse does this by simulating a web page on a user's device and a mid-tier machine.

To further delve into how to conduct audits and optimize your Next.js application, let's discuss the following steps:

Step 1: Install Lighthouse

First, you need to install Lighthouse. It can be downloaded directly from the?Chrome Web Store?or run from the command line.

Using?npm, Lighthouse can be installed via:

npm install -g lighthouse        

Alternatively, in Google Chrome you get Lighthouse right out of the box; to access it visit any website and right-click to open the browser’s menu, scroll down and click on inspect, to open Chrome’s dev tool panel.

Step 2: Run Lighthouse Audit

After Lighthouse is installed, you can audit your application multiple ways,

1. directly through the installed plugin

1. by running the following command:

lighthouse https://yourwebsite.com --view        

through the inbuilt Lighthouse in the dev tools panel, and clicking analyze page load.

Step 3: Interpret Lighthouse Audit Results

The result of the audit comes in five categories: Performance, Best Practices, Accessibility, SEO, and Progressive Web App. Each of these categories has an array of metrics that make up the total score.

Lighthouse provides a detailed report focused on these key metrics - First Contentful Paint, Speed Index, Largest Contentful Paint, Time to Interactive, Total Blocking Time, and Cumulative Layout Shift. Improving the performance of these metrics leads to a better page speed score.

It provides us with details regarding each metric and which might be the cause for performance issues, it also provides recommendations as to what needs to be improved to achieve better performance and also assigns each recommendation is assigned a priority or severity to indicated implementing them would be more effective in achieving better performance.

Step 4: Leverage Next.js for Performance Optimization

Taking measures based on the audit results can significantly improve your Next.js application performance. Here are some you may consider:

• Code-splitting: Next.js supports automated code-splitting which helps to reduce the size of the JavaScript payload.
• Pre-fetching: Next.js automatically prefetches in the background the code for pages linked with?<Link>?component, enhancing the page-loading speed.
• Server-side rendering (SSR): Next.js allows for pages to be pre-rendered on the server, thus improving the First Contentful Paint.
• Static Site Generation (SSG): You can generate a static site at build-time, enabling the pages to load faster.

Step 5: Implement Caching

Lastly, implementing caching can lead to impressive gains in performance. For Next.js, there are numerous ways to cache data:

• In-memory cache: This involves storing data in the RAM of the server hosting the application.
• CDN (Content Delivery Network) caching: By caching content closer to the users, CDN improves web performance.
• HTTP cache: The use of HTTP headers can help to cache static assets, reducing unnecessary network requests.

Working towards improving your Next.js performance through Lighthouse audits and the mentioned strategies can drive faster load times and, in turn, better user experience. Be sure to analyze all application performance aspects to help you make the right decision. Remember, in performance optimization, every millisecond counts!

This article is written by Ammar Khalid , Full Stack Engineer at Antematter.