Reduce the impact of third-party code Third-party code blocked the main thread for 1,370 ms


Hi all,

I have a customer website that is very slow on mobile. We have GTM set up and all the Pixel, Analytics, Conversion API etc is set up there - we dont have any HTML code in the header or body tag of the website, we use the Google Tools section and have added the GTM ID there but the third party code 'blocked the main thread' and is slowing down the website?

Any ideas?


  • visioncraft
    visioncraft Member Posts: 158 Learner

    Hi there, @Lorna_Blakey! Because there are so many factors that can affect page loading times — eg. the type and amount of widgets you have 'above the fold', what third-party widgets you have on the site, whether you have HTML/CSS/JS code anywhere on the page (not just on the <head>), whether you have complex media such as large images or videos, and many more… — the best way for us to help would be if we could actually have a look at the page. If the site is live, and you can share the link, please do, and we'll have a good look at it for you.