Flickity on DAWN - Very slow page loads on mobile - CLS - First Contentful Paint

Store Design

Topic summary

A user implemented a Flickity-based product slider on Shopify’s Dawn theme using code from a WebsensePro tutorial (modified from JohnFromJotting’s work). While the slider functions correctly, it severely impacts mobile performance metrics:

Performance Issues:

  • First Contentful Paint: 2.6s
  • Time to Interactive: 20.6s
  • Speed Index: 6.9s
  • Total Blocking Time: 1,720ms
  • Largest Contentful Paint: 17.3s
  • Cumulative Layout Shift (CLS): 0.999
  • Additional problems with improperly sized images

Current Status:
The original poster requested help improving page load speeds and asked if others using the tutorial experienced similar issues. They offered to share their store URL via private message for review. Another user later encountered the same CLS problems after implementing the code and asked whether a solution was found. The discussion remains unresolved with no fixes or workarounds provided.

Summarized with AI on November 10. AI used: claude-sonnet-4-5-20250929.
1

Hi,

I’ve implemented code from the following tutorial to have a product slider on dawn theme:

https://websensepro.com/blog/how-to-add-product-slider-in-product-page-of-shopify-dawn-theme/

It appears that the code is a modified version of the following by @JohnFromJotting :

https://jotting.com/shopify/shopify-product-slider

It works but is massively impacts the pageload lighthouse figures for mobile.

Improperly sized images, CLS, etc, etc…

First Contentful Paint: 2.6 s

Time to Interactive: 20.6 s

Speed Index: 6.9 s

Total Blocking Time: 1,720 ms

Largest Contentful Paint: 17.3 s

Cumulative Layout Shift: 0.999

I was wondering if anyone else has used the tutorial or can see from taken a quick look at it, how I can bring my page load speeds up.

HELP!!

Thanks,

Online_Seller

2

@Online_Seller ,

Share your store URL so that I will check..

3

Happy to share via PM.

4

@oscprofesionals Happy to share via PM, but you have PMs disabled.

5

Hello,

I know this is an old topic, but i just posted a similar one.

I also have problems with mobile CLS after implementing this code.

Did you found a solution for this?