[Support request] Mobile Largest Contentful paint

[a1reno]

Hi,

On all my pagespeed insights tests on mobile I seem to be constantly failing the LCP. When I look down at the diagnostics the element it finds is always my featured image on a post.

Could it be that Lazy loading by WP Rocket is making this happen or is there something else going on?

You guys are pretty good at solving this stuff so just wondering if you have any advice on this.

Thanks

[David]

Hi there,

I ran a web page test on 3G Moto Network to provide a better visibility of whats going on ( as Google PSI tells you not a lot):

https://www.webpagetest.org/result/210801_BiDc18_ef07ea8c74a56bf7ea85406c5bc4e607/1/details/#waterfall_view_step1

You can see the image is requested quite early on ( #14 ) – but following that you have scripts loading – pertinent ones are #17 and #24 – which are 3rd party scripts and thats where things slow down.

#17 is the connection to cloudflare, i would have expected that to be preconnected to reduce the DNS lookup times at least.
#24 is media vine – is it possible to defer loading that?

Then if you roll down to the bottom of the graph you will see the Long Tasks – 2 x red blocks, thats the browser trying to deal with the big chunk of JS thats just arrived, and during that time it can’t do anything else. As you can see the ( green dotted line ) LCP cant display until those finish.

I did also notice a couple of times when i tested the site in the Chrome Dev Performance tools, the site never quite finished loading as it continuously tried making advert requests that failed. Now that might just of been me, but if that occurs Google has a hell of a time calculating the true LCP, as it can’t decide on what the LCP is until all content is loaded…..

But i would deal with those 3rd party JS files first.

[a1reno]

Hi David,

That’s really helpful! Thanks for your analysis. I’ve made some of your recommended changes and it’s got a little better.

Thanks again!

[David]

You’re welcome

[Author]

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