Lighthouse: Page Speed Insights Ignores CloudFlare's Rocket Loader

[ScottTravisHartley]

In my mind lighthouse is correct because the JS is no longer render-blocking and this is verifiable in chrome dev tools and some of the other testing tools GTMetrix, and Pingdom also register it as no longer being render-blocking.

But the discrepancy can be quite large when testing lighthouse local due to the rocket loader being ignored on page speed insights.

[connorjclark]

PSI is just using a headless Chrome with a specific user agent. It seems the RocketLoader service from CF has disabled* itself from requests made by this useragent (Mozilla/5.0 (Linux; Android 6.0.1; Moto G (4)) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3963.0 Mobile Safari/537.36 Chrome-Lighthouse). If that's the case, the discrepancy lies with CF. Can it be configured to run for any UA you want?

* I confirmed this by checking for rocket-loader.min.js in the main HTML response body in our internal PSI tool–it did not appear. But I see it from locally in Chrome DevTools.

CF directly references Lighthouse in their blog post for Rocket Loader, so if you bring this to their attention they may prioritize this.

[ScottTravisHartley]

I am not able to, this is probably control on their side I will see if I can bring this to their attention since that's a silly thing to do on their part. My guess this was probably a workaround for old-school PSI when it wasn't running on lighthouse.

[connorjclark]

Feel free to comment if you have any information to share from CF. Gonna close this as there's no action item for LH.

[sejoker]

We are planing to allow Page Speed Insights to run RocketLoader.

[KeesCBakker]

We are planing to allow Page Speed Insights to run RocketLoader.

Any news on a time line?

[sejoker]

We are planing to allow Page Speed Insights to run RocketLoader.

Any news on a time line?

Rocket Loader should run during Page Speed Insights testing.