CODEWITHSUNDEEP
pagespeed-insightscls
FijObb
FijObb

Reputation: 1

PageSpeed Insights - CLS on field data not improving

We implemented CLS optimization 20 days ago, actual values (lab data) are perfect from that time. CLS on field data is different story. It is improving but very very slowly. If it is truth that it is calculated out of 28-day period, then we might see significantly better values.
We started with CLS of 1.06 and now we are on 0.68. Lab data on my computer shows CLS of 0.001 Is there any way to validate field data calculation? Or is there any other reason I am not seeing? Thanks.

Upvotes: 0

Views: 348

Answers (1)

GrahamTheDev
GrahamTheDev

Reputation: 24835

First after 20 days a CLS drop from 1.06 to 0.68 is good, you should level out at about 0.5 which is a big improvement.

Unfortunately the reason you have CLS issues is that you still have problems somewhere.

You see the synthetic lab tests only measure initial page load for CLS at 2 specific screen sizes.

The field data measures until page unload and at every screen size.

So your problem is either further down the page or caused by CLS at a different screen size than those tested.

As you have "maxed out" the synthetic tests the advice in this answer I gave may help you identify CLS issues, which covers 2 ways to test using developer tools and how to track real world data (the best way in my opinion) to help narrow down the cause.

Upvotes: 1

Related Questions