Why are new app.latest JS files affecting page speed?

Technical Q&A

Topic summary

Merchants are experiencing significant drops in Lighthouse page speed scores (from 90+ to 75) due to large Shopify-generated JavaScript files, particularly app.latest files from cdn.shopify.com/shopifycloud/checkout-web/assets/.

Key Issues:

  • Files appear to be core Shopify assets consuming 800kB+ of network payload
  • Loading on every page, even outside checkout flows
  • Merchants have no control over these files or ability to optimize them
  • The specific purpose and utility of these assets remains unclear

Current Status:

  • Multiple users report similar problems with checkout-web assets
  • One response provided generic optimization tips (image compression, minifying CSS/JS, removing unused apps) but didn’t address the core Shopify files
  • Community members are seeking official clarification from Shopify on why these large assets are necessary site-wide and whether they can be delayed or optimized

Unresolved: The discussion remains open with no official Shopify response explaining the files’ purpose or providing solutions for the performance impact.

Summarized with AI on November 14. AI used: claude-sonnet-4-5-20250929.
2

Hello @mfcss ,

I am Gina from flareAI app helping Shopify merchants get $5Million+ in sales from Google Search, on autopilot. Hope you are having a good day.

The JavaScript file you highlighted in the screenshot is likely a core Shopify file that is required for the proper functioning of your online store. In general, it’s not recommended to delay or avoid loading core files, as doing so could result in site functionality issues.

However, there are a few things you can do to improve your page speed.

  1. Optimize your images
    Large image files can significantly slow down your page load time. Make sure that your images are compressed and optimized for the web.

  2. Minimize HTTP requests
    The more HTTP requests your site makes, the slower it will load. Try to minimize the number of requests by combining multiple files into one, reducing the number of images on your page, and using CSS sprites.

  3. Enable compression
    Compressing your files can reduce their size and speed up your site’s load time. You can enable compression through your server settings.

  4. Minimize CSS and JavaScript
    Large CSS and JavaScript files can slow down your site. You can minimize these files by removing whitespace, comments, and unnecessary code. You can also consider using some tools to automate this process.

  5. Remove all unwanted Shopify Apps which you are not using
    You should disable app features you don’t use, or you can remove the app if you don’t need it. If you are removing an app make sure to remove code that was added as part of the app install process.

  6. Always choose a theme that is responsive, fast, and takes minimal time to load the page
    If you choose a theme with numerous sliders, fancy animations, advanced navigation systems, etc., will affect your page speed. If your theme is loading slow, consider disabling the theme features you don’t need.

Let me know if you have any further questions.

Gina