Archived topic
Growing FID on mobile devices
43 replies · Started by Kathrin on March 10, 2021
I have a problem with the Page Speed Scores for mobile devices and I can't find the reason for it :( At first I thought that Google Analytics that was loaded in the Head of the cookie consent plugin was the problem because it caused a very high Total Blocking Time. In the meantime I have removed Google Analytics and I have absolute normal Total Blocking Times - everytime in the green field. But the FID is still growing. The initial FID score has been 97% green and 3% orange 3ms in the origin data. Since 27.02.2021 the FID is growing and is now at 73 (green) 26 (orange) and 1 (red) and 155 ms. Do you have any idea what is causing that high FID?
I found out that the FID is not measureable but it correlates with Total Blocking Time and Time to Interactive. But both scores show no issue. I'm really desperate because I have lost the Web Core Vitals status passed because of the growing FID :(
Greetings Kathrin
Hi there,
Slow FID is primarily related to a large amount of, or complicated Javascript being loaded - lots of details on that here:
Some tips:
Combining JS files may be an issue - as several smaller JS files can be loaded and processed faster then a one large file.
Check with JS files are causing the issue by temporarily disabling plugins. If one particular plugin is causing the issue then you may want to look for a more efficient plugin.
If possible defer any Javascript that DO NOT effect user interaction and are not required on page load.
Dear David, thank you for your answer. I already know the web.dev-page :( I don't know which plugin causes the issue. It started when activating Borlabs Cookie Consent Tool but after havin a lot of issues with it, I will try Complianz. Borlabs is also causing the high DOM-size :(
Greetings Kathrin
Complianz has a lot of installs and good reviews - so it sounds like a good choice :)
I have moved from Borlabs to Complianz, I'm using WP Rocket instead of Merge+Minify+Refresh, I have deactivated all javascript files that are not necessary on certain pages and I still have a growing FID on mobile. I can't localize the problem. :(
On mobile there occur 3 long tasks:
https://www.topfgartenwelt.com/wp-includes/js/jquery/jquery.min.js?ver=3.5.1
https://www.topfgartenwelt.com/wp-includes/js/jquery/jquery.min.js?ver=3.5.1 It seems to appear twice with different durations: 112 ms and 90 ms, and
https://www.topfgartenwelt.com/holzzaun-sichtschutz-garten itself.
Blocking Time and Time to Interactive is low.
Javascript is not combined.
What should I do, to get the FID on mobile down?
Greetings Kathrin
Hi Kathrin,
This is a hard one for us to debug, unfortunately, as it's not specific to GeneratePress itself.
One thing you might want to do is deactivate your other plugins one by one and test each time - it may help you pinpoint a problem plugin if it exists.
Hi, thank you for your response. The only two plugins that I installed before the problem with the FID arose, are Lightweight Social Media Buttons and Scriptless Social Sharing. It seems that both only load CSS. Can this also cause FID?
Greetings Kathrin
The vast majority of FID issues are Javascript related. Long loading scripts will block the interaction. So it won't be either of those plugins... one long loading script i can see comes from the statify plugin - may be worth testing the site with that disabled.
Dear David, thank you very much. I have deactivated Statify. It's weird, because I have installed it after the FID has began to grow ...
Greetings Kathrin
FID is a really complicated issue to diagnose ... anything that consumes the browser processing time without any breaks will block Inputs.... as Tom advise you may need to disable some other plugins to see if any are adding extra load.
I know :( and I can't tell you how annoyed I'm already be that nothing works the way it should. To find CLS and LCP is one thing but this is hardcore.
Greetings Kathrin
It certainly is ... you may find you will see improvements when Google starts collecting Field data as most users will have been devices then what Google uses to simulate the results.
This two files are marked as render blocking:
https://www.topfgartenwelt.com/wp-includes/css/dist/block-library/style.min.css?ver=5.6.2
https://www.topfgartenwelt.com/wp-content/themes/generatepress/assets/css/main.min.css?ver=3.0.3
I have just minified the CSS and Javascript in WPRocket. Is there a file that should be excluded from the minification? CSS or Javascript?
Greetings Kathrin
Render blocking CSS files should have no impact on FID.
Sorry i missed your comment here regarding the two jquery requests. It would be good to ascertain which plugins are making the jQuery requests as having two is not good.
Oh my God it is a good question what plugins are doing that. I have activated optimize css now, but didn't combine the css. Do you you think that can cause any problems? At the moment I can't see any (for example CLS).
Maybe I find it out.
So, if I deactivate Complianz (Cookie Consent Plugin), I get the following information:
compress JavaScript: https://www.topfgartenwelt.com/wp-includes/js/jquery/jquery.js?ver=1.12.4
remove unused JavaScript: https://www.topfgartenwelt.com/wp-includes/js/jquery/jquery.js?ver=1.12.4
avoid long tasks: https://www.topfgartenwelt.com/wp-includes/js/jquery/jquery.js?ver=1.12.4 and https://www.topfgartenwelt.com/wp-content/themes/generatepress/assets/js/main.min.js?ver=3.0.3
One long JQuery task is gone after deactivating Complianz, but other problems with Javascript arise :(
If I activate again, there are 3 long tasks, 2 JQuery tasks, but another version: https://www.topfgartenwelt.com/wp-includes/js/jquery/jquery.min.js?ver=3.5.1
One JQuery Task seems to be related to Rankmath.
What does that mean?
Greetings Kathrin
