Frontend Performance25-40 min
Preload Misuse Fix
Use preload only for resources needed immediately, switch future-navigation assets to prefetch, and remove hints that compete with the first render.
HTMLNext.jsViteChrome DevTools
Prerequisites
- A page showing preload warnings or slow first render.
- Access to the HTML head, framework metadata, or document template.
- Chrome DevTools Network and Performance tabs.
1
Plan the implementation
Start by choosing the exact page, route, API, or deployment surface you want to improve. A narrow target makes the implementation measurable and easier to verify.
- Write down the current behavior and the user-facing problem it creates.
- Pick one measurable success signal such as bundle size, latency, error rate, security coverage, or UI responsiveness.
- Identify the files, routes, providers, and environment variables involved.
- Create a rollback note before changing production-sensitive configuration.
2
Set up the required tools
Install or configure only the tools needed for this implementation. Keep config close to the feature so future developers can find the moving parts quickly.
Implementation snippet
npm run build
npm run preview
# In Chrome DevTools, open Network and enable Disable cache.Checklist
- Dependencies are added to the correct workspace package.
- Environment variables are documented in `.env.example` when needed.
- Local development still starts without production-only secrets.
- The change is small enough to review in one pull request.
3
Implement the core pattern
- Open the page and list every `rel="preload"` entry from the final HTML.
- Keep preload only for fonts, hero images, or scripts required in the current viewport.
- Make sure every preload has the correct `as` value and matching `crossorigin` when required.
- Change next-page or maybe-later assets to `prefetch` or remove the hint entirely.
- Reload the page and confirm the unused preload warning is gone.
Implementation snippet
<link rel="preload" href="/fonts/inter-var.woff2" as="font" type="font/woff2" crossorigin>
<link rel="preconnect" href="https://api.example.com">
<link rel="prefetch" href="/dashboard" as="document">4
Handle edge cases
Checklist
- No preloaded asset remains unused a few seconds after load.
- Fonts use `as="font"`, a real font MIME type, and `crossorigin` when served cross-origin.
- Hero images are not lazy-loaded and have intentional priority.
- Payment or chat SDKs load only on pages/actions that need them.
5
Verify before production
- Run the app locally and test the normal success path.
- Test one failure path, one empty state, and one slow-network or retry path.
- Run the project build and any related unit or integration tests.
- Check browser console, server logs, and network responses for hidden warnings.
- Document the final behavior, commands used, and any follow-up work.