Troubleshooting Vercel Speed Insights

If you are experiencing a situation where data is not visible in the Speed Insights dashboard, it could be due to a couple of reasons.

How to fix:

1. Double check if you followed the quickstart instructions correctly
2. Check if your adblocker is interfering with the Speed Insights script. If so, consider disabling it

If /_vercel/speed-insights/script.js is correctly loading but not sending any data (e.g. no vitals request), ensure that you're checking for the request after navigating to a different page, or switching tabs. Speed Insights data is only sent on window blur or unload events.

Speed Insights may not function when using a proxy, such as Cloudflare.

How to fix:

1. Check your proxy configuration to make sure that all desired pages are correctly proxied to the deployment
2. Additionally, forward all requests to /_vercel/speed-insights/* to the deployments to ensure proper functioning of Speed Insights through the proxy