Returning visitors download your files again every time
Static assets served without caching headers
What this means
Your scripts and stylesheets come without caching instructions, so a browser that already has them downloads them again on the next visit instead of reusing what it stored.
Why it matters
Repeat visits stay as slow as the first one, and your server pays for traffic it did not need to send. On a site people return to, this is the difference between an instant page and a full reload every time.
When this is not a problem
HTML itself is usually meant to stay uncached so visitors see fresh content. This check looks at build assets — scripts and stylesheets — not the page.
How to fix it
- Serve build assets with a long Cache-Control max-age, for example one year.
- Make sure asset file names contain a content hash so a new build gets a new name — then long caching is safe.
- Keep the HTML itself short-lived so visitors still get new releases immediately.
Prompt for your AI agent
Static assets are served without Cache-Control. Add long-lived caching for hashed build assets and keep the HTML uncached.
How to verify the fix: request a script or stylesheet and confirm it carries Cache-Control
References: developer.mozilla.org