How To Fix Slow Page Load Times After Shopify Theme Update?

Store Design
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1

After Updating my Shopify theme, I have noticed a significant drop in page load speed, especially on Product pages. I have tried image compression and lazy loading, but the speed still isn’t great. I ran a test with google PageSpeed Insights, and it pointed issues with JavaScript and CSS rendering.
Has Anyone Faced this issue after a theme update? What steps did you take to improve page speed?
Any specific apps or settings that helped ?

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hey @robert.charles share the URL of your website

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Url : https://roobotech.com.au/

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hey @robert.charles i don’t think so there is any problem in your product page or any collection page because in my side your website i working properly i think you have a internet issue in your side plz check this issue or if you have any other question feel free to share it or if your problem is solved don’t forget like and mark as solution
Best
Mustufa

5

Thanks for your input!
It seems like it might be a network issue on my end. I will try restarting the router and check the site again to see if the issue persists. If it continues, I will reach out again.

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I see it’s Dawn 11.0.0 (while current being a 15.4.1)
What you’ve upgraded from?

Also, is it just feels slow or actual Shopify reports show worse Lighthouse scores?

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@robert.charles

I also saw a big PageSpeed drop — mainly due to increased JS & CSS.
• Deferring non-critical JS
• Removing unused app scripts
• Inlining critical CSS
• Optimizing fonts & images

Product pages suffer most because of galleries, reviews & add-ons loading extra scripts.

pagespeed
pagespeed604×833 51.3 KB

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Hi

I checked your site on https://roobotech.com.au/ on the Google PageSpeed Insights https://pagespeed.web.dev/analysis/https-roobotech-com-au/g8d4tyyoho?form_factor=mobile . It looks like product page speed is affected by large images, render-blocking CSS, and JavaScript running on all pages.

A few things that usually help :

  • Optimize Images - Compress and use WebP

  • Load JS on Demand - Defer Non-Essential JavaScript :

  • Preload Key Visuals – Help main banners or product images appear faster:
    These improvements will help your site load quicker, perform better on mobile.

If performance issues persist ,there are third party Shopify apps that can handle optimization and improve performance .

Disclaimer : I’m associated with Website Speed . It’s optional to use .