Faster Loads with Smaller Bundles: The Power of Dynamic Imports in Next.js

In today’s web world, speed is everything. Users expect pages to load instantly, and even a slight delay can lead to frustration or bounce. One big factor that impacts performance is your app’s bundle size - the amount of JavaScript the browser has to download and execute before the page is usable.

So let’s talk about something simple, yet super effective: Dynamic Imports in Next.js

Why Should You Care About Bundle Size?

A large JavaScript bundle means:

• Longer download times, especially on slow connections
• Delays before the app becomes interactive
• Poor performance scores and user experience

On the flip side, a smaller bundle means faster loads, snappier UI, and happy users.

What is a Dynamic Import?

In a typical React or Next.js app, components are imported at the top of the file like this:

import MyComponent from './MyComponent';

This means the component is bundled into the main JavaScript file, whether it’s used immediately or not.

With Next.js, you can use next/dynamic to import a component only when it’s needed:

const MyComponent = dynamic(() => import('./MyComponent'));

Example: With vs Without Dynamic Import

Let’s say we have a simple page that includes three components:

1. A Button
2. A Test Component
3. A Hidden Component (only shown after a button click)

Without Dynamic Import

"use client";
import { useState } from "react";
import HiddenComponent from "../components/HiddenComponent";
import TestComponent from "../components/TestComponent";

export default function WithoutDynamicImport() {
  const [displayHiddenComponent, setDisplayHiddenComponent] = useState(false);

  return (
    <div>
      <h3>Without Dynamic Import</h3>
      <button onClick={() => setDisplayHiddenComponent(!displayHiddenComponent)}>
        Show Hidden Component
      </button>
      <TestComponent />
      {displayHiddenComponent && <HiddenComponent />}
    </div>
  );
}

In this version, all components are imported statically. Even if the HiddenComponentis never shown, it still gets bundled and downloaded upfront

With Dynamic Import

"use client";
import dynamic from "next/dynamic";
import { useState } from "react";

const HiddenComponent = dynamic(() => import("../components/HiddenComponent"), {
  ssr: false,
});

const TestComponent = dynamic(() => import("../components/TestComponent"), {
  ssr: false,
});

export default function WithDynamicImport() {
  const [displayHiddenComponent, setDisplayHiddenComponent] = useState(false);

  return (
    <div>
      <h3>With Dynamic Import</h3>
      <button onClick={() => setDisplayHiddenComponent(!displayHiddenComponent)}>
        Show Hidden Component
      </button>
      <TestComponent />
      {displayHiddenComponent && <HiddenComponent />}
    </div>
  );
}

In this version, TestComponentand HiddenComponentare loaded only when needed. You’ll even notice separate .js files being fetched in the browser when these components render for the first time

What Happens Behind the Scenes?

When you use dynamic imports:

• The component is excluded from the initial JS bundle.
• A separate network request is made only the first time the component is needed.
• Once loaded, the component is cached by the browser, so subsequent uses do not trigger another network request.
• This leads to faster page load, and better user experience.

Wrapping up

Dynamic imports are a smart and simple way to keep your Next.js app lean and fast. By loading components only when they're actually needed, you:

• Reduce your initial JavaScript payload
• Improve performance and speed
• Make your app more scalable as it grows

Start using dynamic imports for any non-critical UI - like modals, charts, tooltips, and components hidden behind interactions.