The Need for Speed: Next.js Performance Overhaul with Polyfills and SWC
Tags: webdev, nextjs, performance, javascript
Published: 2023-08-28 18:17:00

In the fast-paced world of web development, staying up to date with the latest tools and technologies can make all the difference in delivering a cutting-edge user experience. As a frontend web developer, you're likely familiar with the Next.js framework, known for its ease of use and server-side rendering capabilities. However, did you know that a simple upgrade to the latest version and a couple of strategic changes can lead to a significant boost in your app's performance? In this blog, we'll delve into a real-world case study of upgrading a Next.js production app, uncovering how a version update, elimination of duplicate polyfills, and the embrace of the SWC compiler can revolutionize your app's loading speed and development workflow.


## Removing Duplicate Polyfills: Streamlining Browser Support
Polyfills are essential components in web development, bridging the gap between modern functionality and older browsers that lack native support. However, not all polyfills are created equal, and redundancy can creep in, impacting your app's performance. Next.js, being a forward-thinking framework, already comes equipped with polyfills to cater to modern browsers without any additional configuration. This means you can trim down your app's payload by getting rid of duplicate polyfills.

In the latest versions of Next.js, targeting specific browsers or features is a breeze using the [Browserslist](https://browsersl.ist/) configuration in your package.json file. The latest version of Next.js (v13) uses the following configuration by default:

```json
{
  "browserslist": [
    "chrome 64",
    "edge 79",
    "firefox 67",
    "opera 51",
    "safari 12"
  ]
}
```
By aligning your polyfills with the supported browser versions, you ensure optimal performance for your target audience while shedding unnecessary code weight.

## Embracing the SWC Compiler: Unleashing Rapid Compilation

![SWC Logo](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/pjbm2naq5k3uoyeyr2tn.png)

Next.js has long been a staple for server-rendered applications, but as the demand for faster development cycles grows, so does the need for speedier compilation times. Enter the SWC compiler – a Rust-based powerhouse that transforms your modern JavaScript code into a format that can run seamlessly across various environments, all while outperforming the traditional Babel transcompiler.

![SWC performance metrics](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/z7aqdcd77j3kvild4azo.png)

The switch from Babel to SWC in Next.js v12 opens the doors to a realm of performance improvements. SWC leverages Rust's low-level prowess to compile and execute faster than its JavaScript-based counterparts. [Performance benchmarks](https://swc.rs/blog/perf-swc-vs-babel) consistently demonstrate SWC's superiority, making it a clear winner when it comes to delivering blazing-fast compilation times. With SWC, your development workflow gets a turbo boost, with up to **5x faster** Fast Refresh – enabling you to iterate and refine your code with unparalleled efficiency.

## The Power of Real Production Insights
Let's dive into a real-world scenario that highlights the transformative power of these upgrades. Our Next.js app, living in the wilds of production, grappled with an initial load JavaScript size exceeding 160KB. Through a meticulous upgrade process, a judicious removal of redundant polyfills, and the introduction of the SWC compiler, a spectacular transformation unfolded. The initial load size nosedived to under 110KB – an impressive _**30% reduction**_ that wasn't just about digits, but about delighting users.

![High Speed Car](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/f50vkued3ea7mdz29i3h.jpg)

The implications were profound. A leaner initial load empowered our app to race onto screens, offering lightning-fast experiences even on devices and connections that had previously posed challenges.

## Conclusion: Elevate Your Next.js App to New Heights
As a frontend web developer, your journey involves constantly pushing the boundaries of what your apps can achieve. Upgrading your Next.js project, eliminating redundant polyfills, and adopting the SWC compiler represent pivotal steps in this evolution. With these changes, you're not only optimizing performance but also redefining your development workflow. Your app becomes a testament to cutting-edge technology, delivering unrivaled speed and responsiveness to your users.

![cutting-edge technology](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/6d5c3s27bhb4exfunyx5.jpeg)

So, what are you waiting for? Take the leap, embrace these enhancements, and watch your Next.js app soar to new heights. Your users and your development team will thank you for the snappy experiences and streamlined workflows that lie ahead. It's time to turbocharge your Next.js app and leave a trail of awe-inspiring performance in your wake.