FCP & LCP is longer than Visually complete

Could you please explain how the WPT gathers the metrics?

I’m a little confused because in my tests I often face that FCP&LCP is longer than Visually Complete in 2-3 times.

Hello Tom,

I see you have already raised a support ticket and I want to let you know that we’re actively investigating the issue. We’ll keep you posted with updates both here and in the ticket as we work to resolve it.

If you have more details to share, please feel free to reach out.


FWIW, FCP and LCP are reported by Chrome’s internal measurements and “Visually Complete” is captured from the video. If you have a test you can look at, you can look at the filmstrip and see if you can tell what is going on. Usually the problem is the other way around and FCP/LCP can report before “start render” which can be confusing.

Main thing that comes to mind is if the FCP and LCP elements are an image (specifically, a progressive JPEG) then FCP and LCP will only report for that element when it is completely done rendering but it might be visually “done” a lot sooner (usually around 1/2 of the image bytes looks quite good).

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