For storefront features, load only on the pages where they are needed, minimize JavaScript, avoid duplicate libraries and defer nonessential work. Reserve space for widgets to prevent layout shifts, and keep heavy work away from user interactions. A small script can still hurt responsiveness if it runs too often.

For the app backend, request only necessary fields, paginate large datasets, cache safe repeated reads and move slow synchronization into background jobs. Make caches store-specific and invalidate them when the underlying data changes.

Compare the same representative pages before and after installation on a mobile connection. Check loading, interaction latency and layout stability, then confirm that variants, cart actions and accessibility still work. Use real-user measurements where possible rather than treating a single Lighthouse score as the whole result.

What is currently slow: opening the app in Shopify admin, rendering a storefront widget, or processing data?