Why did my page speed significantly decrease without any apparent reason?

Shopify Partner
18 0 3

Hi Dear community,


For some unknown reason I noticed that our page speed decreased from 20 to 5 (from 15th of December on). 

I checked the activity log in shopify, but I couldn't detect any suspicious activity (installation of App e.g). 


I do not understand the cause of this. I am aware that third party apps and big sized media can slow it down. But in term of Media, I made sure no file is above 300kb. I assume the cause might be related to a third party app, but i cannot figure out which app this is. 


We recently set up a CDN connection (redirection to subdomain in order to enable translation) could this be the reason maybe?


My reference is google lighthouse and shopify. And lighthouse shows especially a slow mobile page. 




Is there a way to figure out, what app or what exactly causes this decrease ? 


**Addition: During Xmas time (starting on the 17th of december when it decreased) the Page Speed from Google Lighthouse showed 7 (mobile) and its up to 20 again (still bad). Assumably this was also due to high visitor number maybe, so our mobile storer can not take up with such a high request and therefore performs badly? If this is true, why does it take such a long time to recover ? 


Any help is much appreciated.


Replies 2 (2)

Shopify Partner
15895 2377 3082

Hi @roundabout ,

I have checked your site in the page speed tool. your website score is very low.


3rd party apps & codes which take time to load and their size . They decrease the speed.


Need to work on following points 

  • Theme Upgrade if there is a scope and upgraded theme available
  • Reduce JS Payload.
  • Use Critical CSS .
  • Reduce Large Image Sizes
  • Compress Images
  • Limit Third Party JavaScript & Shopify Apps
  • Preload Web Fonts. 
  • I would suggest limiting to one and using a standard web font.

See where exactly google speed index tools want you to target your code to optimize the site .

First Contentful Paint

  • Eliminate render-blocking resources
  • Reduce server response times (TTFB)
  • Avoid multiple page redirects
  • Preload key requests
  • Avoid enormous network payloads
  • Serve static assets with an efficient cache policy
  • Avoid an excessive DOM size
  • Minimize critical request depth

Time to Interactive TTI :

Time to Interactive (TTI) is one of six metrics tracked in the Performance section of the Lighthouse report. Each metric captures some aspect of page load speed.

Total Blocking Time: 

  • Reduce Unnecessary JavaScript loading, parsing, or execution.  
  • Reducing JavaScript payloads with code splitting, removing unused code, or efficiently loading third-party JavaScript.

Speed Index

  • Minimize main thread work
  • Reduce JavaScript execution time
  • Ensure text remains visible during webfont load

Largest Contentful Paint

LCP is primarily affected by four factors:

  • Slow server response times
  • Resource load times

Cumulative Layout Shift

  • Cumulative Layout Shift measures the movement of visible elements within the viewport

By fixing these issues, your website speed score can definitely improve.

And we will provide an assured guarantee plan for the website speed optimization.

For more details please check the link below. 


If anything is missed out or unclear then don't hesitate to ask. Email us or Connect with us on Skype

Have a nice day !

Get pass your Store Core Web Vital Free Speed Optimization Audit, Chat on WhatsApp | Skype : oscprofessionals-87 | Email: pallavi@oscprofessionals.com | Hire us | Guaranteed Site Speed Optimization | Website Free Audit | Shopify Theme Customization | Build Shopify Private App | Shopify SEO | Digital Marketing | Oscp Upsell & Cross sell App : Free | Oscp Sales & Volume Discount App : Free | Custom Pricing Wholesale App : Free

Shopify Expert
695 52 135

Hi @roundabout 


I am Alex From MS Web Designer (Top Rated Shopify Certified Experts and eCommerce Consultant from Singapore ) I helped 1000+ Shopify Store owners to Optimize their website loading speed for both mobile and desktop and increase their conversion rate.

Here are some proven steps that will improve your website speed dramatically for both mobile and desktop.

  • Select a light Weight Shopify Theme ( OS 2.0 Compatible
  • Remove all Unwanted Shopify App ( That you have installed, but not using)
  • Minify Javascript, CSS 
  • Reduce the Large Image Size
  • Eliminating the halting problem in Javascript
  • Apply Lazy loading per section wherever required
  • Replace Gifs with the Static Images
  • Resize Products images using Shopify App ( for Bulk )
  • Check Page Speed by Google page Insight and GTmetrix.

By fixing these issues, your website speed score can definitely improve
If you want a Free complete Website Optimization Audit Report ( All the Actionable steps for your store ), let me know 


If you have any concerns feel free to ask me!

Good Luck!