Hi @NextLevel, I’ve seen slight performance dips here and there before, but not anything that dramatic or sustained. 

Klaviyo (klaviyo.js) code is technically non-blocking (asynchronous) from my past inspections, but you may want to figure out if there are any runtime errors on your landing pages (Facebook Destination URLs) that might be blocking Facebook Tracking pixel/events from firing.  This depends highly on how your Shopify Templates were implemented so it’s hard to point to a specific reason why you’re encountering this issue.

In case you’re not aware, Facebook has a Pixel Helper tool that might also help diagnose any issues with the event tracking: 

• Pixel Helper (developer.facebook.com)

As a last resort, if you are using Klaviyo’s automatic Javascript injection into the Shopify Theme (checkbox in the Klaviyo Shopify Integration Settings), you may want to consider placing it manually so you can re-order where Klaviyo’s code is placed. 

• How to Manually Install Klaviyo.js for Shopify Stores

However, I would do this as the last resort if you can’t figure out why the Facebook Tracking Pixel isn’t firing consistently.  Remember, it’s not impossible for Facebook Ad Manager to sometimes under-report, have bugs themselves which might catch up in a day or two.  

Hope that helps you find the solution!

Hey @retention !

Thanks for taking the time to answer. That helps a lot. 

We are digging deeper into the topic and if there is anything else we discover, I’ll add it here. 

Best

Hendrik