What it means
We flag pages where code and files from other domains exceed 500 KB per page on average, or more than 30% of all downloaded bytes.
Why it matters
Third-party scripts compete with your own content for bandwidth and the main thread, and you don’t control how heavy they are or when they change.
They are also a privacy and security consideration: each one runs with access to the page.
How to find it yourself
- PageSpeed Insights lists third-party code and its impact.
- In DevTools, group the Network panel by domain to see what each service loads.
How to fix it
On any website
- List every third-party service and remove those nobody uses.
- Load the rest after the page is usable: defer, async, or load on interaction (for example, a chat widget after the first click).
- Use a facade for heavy embeds such as video players and maps: a static preview that loads the real embed on click.
On Shopify
- Review installed apps and app embeds; uninstalling an app doesn’t always remove its theme code.
On WordPress and WooCommerce
- Check plugins that add tracking, chat or social widgets, and load them only on the pages that need them.
How to check the fix
- Run the speed test again and compare the share of bytes from other domains.
How FixReports finds it
The speed test groups every download by domain and reports the share and size of bytes from domains other than yours.