App scripts blocking render

Shopify mistakes

What it means

Synchronous app scripts in the head delay paint and add tens to hundreds of ms to LCP.

Why it happens on Shopify

Legacy app injections lack defer; uninstall does not remove leftover code.

How to check if you have this issue

PageSpeed Insights: render-blocking resources report.

Related issues

• Monolithic JS bundle (> 500 KB)
• Uninstalled apps leaving active code