Slow theme Performance when published, very fast in preview

Shopify Partner
3 0 0

Hi guys,


My store runs slow when I publish the theme, especially the collection page, if I clone the theme and have a preview, it works super fast. Although no changes were applied the theme. 


Published theme:



What could be the reason? 

Shopify Expert
700 53 156

The preview link didn't work for me so I couldn't compare, but I have some ideas:

- some apps inject their scripts into the live theme, rather than including in a snippet. If that's the case, the live theme could load slower if it's a slow / heavy script. You can test by briefly publishing the preview theme and recording the results of each theme when it's live. I recommend for getting load speed / requests / weight results.


- it looks like the slowest loading element is the fb chat widget. If you've ran your test over multiple days it's probably something to do with the first point I made. If it seems random, it may be a widget like this that loads multiple larger resources, sometimes that can cause inconsistencies.

Founder of Speed Boostr (Shopify optimization and dev agency).
Creator of Theme Scientist (A/B testing app).
Creator of Order Automator (app that auto tags + fulfills orders, send emails).
Creator of Tip Jar (add a tip button to your store).
Creator of Shopify Analyzer (free performance analysis tool).
My team also builds custom apps and automated solutions.
Enjoy the adventure!