It looks like all the sites who use Prismic get a terrible score at Page Speed Insights.


  1. Is Prismic really slowing down all the sites that use their CMS? List of sites using Prismic

  2. Score on Page Speed Insights is constantly changing. One second it gives us a score of 19 out of 100, sometimes 5 out of 100. Does that have to do anything with the traffic on the server?

Extra info: our site is built with Vue Js.

1 Answer 1


I work on the Developer Experience team over at Prismic, so I might be able to help answer your question!

When I run some of these sites through PageSpeed insights, it's true that some aren't scoring well, but we need to look at what the cause is.

Looking at one on the list you provided, their biggest issues are "Reduce unused JavaScript" (5.25s) and "Defer offscreen images" (5.1s).

For unused JavaScript the script culprits are:

  • bigcommerce
  • smooch.io/zendesk
  • yotopo
  • Facebook
  • jQuery
  • helloextend
  • bigcommerce (again)
  • YouTube
  • bigcommerce (again 2x)

And so on. Mostly scripts around e-commerce and tracking. These are all additional scripts that were added to the site and have nothing to do with Prismic. No matter what CMS you're using, if you add these scripts to the site, it would still have the same impact on load time.

If you look at "Defer offscreen images", that can be solved by lazy-loading images 'below the fold' so that the page can load faster and call those as needed.

Prismic helps you manage your content and build pages, but shouldn't hinder performance. If anything, a site should be more performant with Prismic for a couple of reasons.

  • Images coming from Prismic get served through the imgix CDN which lets you automatically adjust the quality and format. Large images can really slow down a site, and Prismic helps you avoid that issue!
  • Your API calls get cached on CDNs around the world. If your site/app is requesting data client-side, your users are going to get a cached response from a server close to them, greatly speeding up the response time.

Additionally, many sites these days get built and served statically. Next.js, Gatsby, and Nuxt 2 all support this feature. This means that Prismic is only called at build time and when the user requests the page, it's already been built.

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