CODEWITHSUNDEEP
htmlpagespeed-insights
Denis Bogdanov
Denis Bogdanov

Reputation: 1

Hight First Input Delay (FID) measure on an empty page. (No js, no css)

I am trying to improve the FID measure for my wordpress website with no success.

Whatever I do the "pagespeed insights" tool shows FID over 100ms on the Mobile tab.

The desktop tab shows ~4ms.

Finally I have just created an html file with 1 line of text no js, no css, just a single line of text.

I have uploaded the file to the same server and the FID is still over 100ms on Mobile. How can it be?

https://www.extra.co.il/wp-content/themes/extra/test.html

https://developers.google.com/speed/pagespeed/insights/?hl=iw&url=https%3A%2F%2Fwww.extra.co.il%2Fwp-content%2Fthemes%2Fextra%2Ftest.html

Upvotes: 0

Views: 284

Answers (1)

GrahamTheDev
GrahamTheDev

Reputation: 24885

Origin Summary is taken over a 28 day rolling average across every page on the site.

Simply uploading a test file will not change that as it is based on real world data and is not part of the synthetic test.

In the "Lab" section (the synthetic test) you will see "Total Blocking Time", that is the equivalent metric for First Input Delay and you will see it is at 0ms (as there is no JavaScript blocking your test page).

The reason the desktop performs better is down to processing power, mobile phones typically run 2x-8x times slower than a desktop CPU so it is expected that the First Input Delay is going to be higher on mobile.

Yet again that is real world data on a 28 day rolling average so you can't make a change today and see the results immediately.

For this reason I would suggest using the web vitals library to gather real world data in real time rather than relying on the data coming from the CrUX dataset (which is what Page Speed Insights is using to display the "Origin Summary".

Upvotes: 0

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