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To let Next.js associate a dynamically imported component with its chunk for preloading, declare dynamic() at module scope and put a literal import() path inside its loader. This is documented behavior for the Pages Router; it does not guarantee a particular latency improvement. Verify the behavior in a production build and measure when the chunk request starts and how the component’s first use feels.
Use a module-scope dynamic declaration with a literal import path
In the Pages Router, Next.js documents this pattern for a dynamically imported component:
import dynamic from 'next/dynamic'
const DynamicChart = dynamic(() => import('../components/Chart'), {
loading: () => <p>Loading chart…</p>,
})- Declare the
dynamic()call at module scope, rather than inside a component or another function. - Keep the import path literal and explicit. Do not construct it from a variable or template string.
- Provide a loading UI when deferred content may take time to appear.
Next.js explains that the import() must be inside the dynamic() call so it can match webpack bundle and module identifiers to that call and preload before rendering. This guidance is specifically stated in the Pages Router lazy-loading guide; check your installed Next.js version if applying it to a version-specific setup.
Check the App Router component boundary
The App Router guide describes next/dynamic as a combination of React.lazy() and Suspense and shows conditional loading patterns. But Server and Client Component boundaries affect what can actually be split:
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- Automatic code splitting is not supported when a Server Component dynamically imports a Client Component.
- Dynamically importing a Server Component does not itself lazy-load that Server Component. Its Client Component children are the parts that can be lazy-loaded.
ssr: falseis supported only in Client Components.
Review where the declaration lives and which component is being imported before treating a delayed load as a chunk-preloading problem. See the App Router lazy-loading guide for the current constraints.
Separate dynamic chunk loading from route prefetching
These mechanisms address different delays. Dynamic-import preloading associates a next/dynamic call with its chunk; route prefetching fetches route assets ahead of navigation. Automatic prefetch applies to Link navigation and runs only in production, with behavior that differs for static and dynamic routes. If the delay happens during navigation, inspect route prefetching; if it happens when a deferred component is first used, inspect the dynamic chunk request. The prefetching guide describes the route behavior.
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Choose deferral based on both initial load and first use
Lazy loading reduces the JavaScript initially needed for a route by deferring Client Components or libraries until they are needed. The tradeoff is that the first use may trigger a later request, leaving the user waiting for the chunk or its loading UI. For an external library used after an interaction, the App Router guide demonstrates native import() on demand; that request begins when the interaction path runs, so it should not be described as already preloaded unless the application separately arranges that behavior.
Do these 3 things before closing this tab:
1Clear out junk files and repair common Windows errors2Scan for outdated or missing drivers - takes under a minute3Repair Windows errors before they cause bigger problemsWhen deciding whether to load eagerly, defer, or arrange earlier loading, compare:
- How much client JavaScript is transferred initially.
- When the chunk request begins in relation to the user action and render.
- Whether first use displays a loading state or delays interaction.
- Whether the declaration complies with the App Router’s Server/Client Component constraints.
- Whether the observed delay is actually navigation-related, and whether you are measuring in production.
The production checklist describes code splitting and route prefetching as defaults and recommends considering lazy loading third-party libraries where appropriate. Avoid adding eager work to the initial path without checking its effect on both initial transfer and first-use behavior.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Verify the fix in a production build
- Build and run the application in production mode; development behavior does not establish how automatic route prefetching behaves.
- Reproduce the specific slow path: navigate to the route, or trigger the interaction that first uses the deferred component or library.
- Inspect the browser’s network activity to identify when the relevant chunk request starts and whether the visible pause occurs before or after it.
- Compare initial JavaScript transfer, request timing, and first-use experience before and after changing the declaration.
- Keep the loading UI and component boundary in view when interpreting the result; a valid preload pattern is not proof of a measured speedup.
The official guides document implementation behavior, but do not provide a benchmark figure for the latency improvement in an individual application. Measure your own production build rather than assuming a percentage or guaranteed reduction.
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