Next Js Bundle Is Large Improve Performance and Speed

The Next.js bundle size can be a major issue, but there are ways to improve performance and speed. Large bundles can slow down page loads and make your application feel clunky.

One of the main reasons for large bundle sizes is the inclusion of unnecessary code. According to the article, Next.js includes all the pages in the bundle by default, which can result in a significant increase in bundle size. This can be especially problematic for large applications.

To improve performance and speed, you can use code splitting to break up your code into smaller chunks. This way, only the necessary code is loaded when a user visits a particular page.

Custom fonts can increase your bundle size, so it's essential to optimize them. Next.js automatically optimizes Google Fonts, but you may need to load other fonts asynchronously or preload them for better performance.

Inspecting your Next.js app bundles is crucial to identify potential issues. The @next/bundle-analyzer package provides various methods to inspect your bundles, including the terminal, browser, and sidebar filter.

Large dependencies can significantly impact your app's performance. Spotting large modules and identifying alternative packages can help reduce your bundle size.

Duplicate code can also slow down your app. Detecting duplicate code and removing unused versions can help optimize your app's performance.

Analyzing bundle size metrics is essential to identify potential bottlenecks. A large stat size, parsed size, or gzipped size can affect your app's performance.

Unused code can also contribute to a large bundle size. Tree shaking can remove unused code, but sometimes, there may be unshakable codes. Inspect your analysis report to confirm that there is no unused code in your bundle.

To optimize your Next.js app's performance, consider the following issues:

To address these issues, you can:

Dynamic imports can also help reduce your bundle size. Instead of loading non-essential UI elements upfront, use dynamic imports to load them conditionally.

Related reading: Nextjs Dynamic

Replacing heavy libraries with lighter alternatives can also reduce your app's bundle size. For example, you can switch from moment.js to date-fns or day.js for handling dates.

Excluding big libraries from your bundle can also help optimize your app's performance. If you're not using a library, make sure to exclude it from your bundle.

To analyze and understand the app, you need to run the Next.js Bundle Analyzer. This can be done by installing the analyzer and modifying the next.config.js file to enable the bundle analyzer. You can then run the command to generate the bundle analysis.

The Next.js Bundle Analyzer provides a graphical representation of your JavaScript bundles, showing the size of each module in your bundles. Larger rectangles represent heavier modules, which take up more space and time to load. You should focus on the Vendor Code, Common Code, and Duplicate Code areas to identify potential bottlenecks and areas for improvement.

By inspecting the bundle analysis report, you can spot large dependencies, detect duplicate code, analyze bundle size metrics, identify unused code, and utilize source maps to optimize app performance. This will help you address issues such as large image file sizes, duplicate npm packages, unused npm packages, and heavy JavaScript files.

For another approach, see: Npm Next Js

Analyzing the app is a crucial step in understanding its performance and identifying areas for improvement. You can start by using the Next.js Bundle Analyzer, which provides a graphical representation of your JavaScript bundles.

The analyzer will show you a list of modules, each represented as a rectangle, with the size of the rectangle corresponding to the module's size in your bundle. Larger rectangles indicate heavier modules that take up more space and time to load.

To run the analysis, start your Next.js app in development mode with the ANALYZE environment variable set to true. Then, run the command npm run analyze, which will open three files in your browser: client.html, nodejs.html, and edge.html. The client.html file represents the client side, while nodejs.html represents the server side.

See what others are reading: Apolloclient Nextjs

The bundle analysis will also provide you with information on the size of each module in your bundles. You can see the size of the JavaScript bundle when served to the client, the parsed size (the amount of memory that the JavaScript code takes up in the web browser after it has executed the code), and the gzipped size (the amount of data the client's web browser must download to run the app).

Here are some key areas to focus on when reviewing the output:

By identifying and targeting the largest chunks of your bundle, you can reduce overall size and improve load times.

You can use the debugger statement to find issues in your bundle. This allows you to debug your client-side code.

Add the debugger statement to your code to pause code execution in the browser's DevTools. You can do this by adding the statement to your code and starting the server with npm run dev or yarn dev.

The --inspect flag is necessary to debug on the server side. Update your package.json to include this flag.

Start your development server again with npm run dev or yarn dev. This will show you a message in your terminal.

Open chrome://inspect in Chrome to see your Next.js application inside the Remote Target section. Click on Inspect to open it in a separate Chrome DevTools window.

The Sources panel is where you can set breakpoints, inspect variables, and step through your server-side code. This helps you identify and resolve issues within your bundle.

Related reading: Nextjs Open Graph

Optimizing app performance is crucial, and bundle analysis is an essential tool for achieving this. It helps identify potential bottlenecks and areas for improving an app's load speed and reducing its bundle size.

Large image file sizes can slow down an app's load speed, so compressing or resizing images is a good starting point. Duplicate npm packages will unnecessarily increase the app's bundle size, so removing them is a must.

Unused npm packages will contribute to the app's bundle size and slow down its load speed, so removing them is also essential. Heavy JavaScript files will add to an app's bundle size, so using minification, tree shaking, and code splitting to optimize JavaScript files is a good idea.

Dynamic imports can reduce the initial load by 10%, which is significant. This simple change can improve the performance score by more than 2.2 points. Using dynamic imports definitely helps, and the result will be even more significant with a more complex page.

Here are some strategies to reduce the size of your Next.js bundle:

By implementing these strategies, you can reduce the size of your Next.js bundle and improve performance.

You can customize the webpack configuration in Next.js by adding the webpack property to your next.config.js file and passing your configurations on to it. This allows you to add loaders, plugins, or other optimization configurations to the webpack.

For another approach, see: Nextjs Webpack

Before making any changes, ensure that Next.js is not already handling such optimizations for you. This will prevent any potential conflicts or issues.

To modify the webpack configuration, you can split vendor libraries into a separate chunk for the client-side bundle. This can help reduce the size of your app bundles.

By customizing the webpack configuration, you can optimize your app bundles and improve performance.

If you're tired of dealing with large Next.js bundles, there's good news: you have options. You don't have to stick with the default tools.

Let's take a look at some alternative solutions. Webpack-bundle-analyzer is a widely-used tool that analyzes bundle size, generating interactive visualizations to help you identify which modules take up the most space.

Another option is next-bundle-analyzer, a community-driven alternative that provides customized reports specifically for Next.js users.

You can also try source-map-explorer, which analyzes bundle size by examining source maps generated during the build process. It provides a treemap visualization of the bundle size, showing where each byte of code is coming from.

Intriguing read: Next Js Alternatives

Statoscope is another web-based tool that analyzes the size and composition of webpack bundles. It provides a simple interface for users to upload webpack stats files and generate visualizations that help identify which modules and dependencies contribute most to the app's bundle size.

Here are some alternatives to consider: