Reduce the impact of third-party code
To add an advertising network, social media button, A/B test, or analytics service to your page, you usually need to add a third-party script to your HTML. These third-party scripts can significantly affect your page load performance.
How the Lighthouse audit for third-party code fails #
Lighthouse flags pages that have third-party code that blocks the main thread for 250Â ms or longer:
A third-party script is any script hosted on a domain that's different than the domain of the URL that you audited with Lighthouse. As the page loads, Lighthouse calculates how long each of the third-party scripts blocks the main thread. If the total blocking time is greater than 250Â ms the audit fails.
How to reduce the impact of third-party code #
See Identify slow third-party scripts to learn how to use Chrome DevTools and other Lighthouse audits to detect problematic third-party code, and see Efficiently load third-party JavaScript for optimization strategies.