Every check is automated, evidence-based, and grounded in Shopify-specific performance patterns. We sample three page types to give you a representative score in under ten seconds.
We issue three sequential requests to each page and inspect the x-cache and ETag headers. A stable ETag confirms the page is served from Shopify's edge cache. Sub-40ms server processing confirms cache-hit behaviour. We also extract Shopify's template complexity score.
Every image is analysed for responsive attributes: srcset, sizes, explicit dimensions, and lazy loading. Hero images are checked for preload hints. Properly sized, lazy images prevent layout shifts and reduce bandwidth.
We count all script tags, flag render-blocking ones without defer/async, and catalogue every external domain. Each third-party origin adds DNS lookups and TLS handshakes. Fewer deferred scripts means faster Time to Interactive.
We scan for preconnect, preload, and dns-prefetch directives. Critical origins should be pre-connected. Hero images and fonts should be preloaded so the browser fetches them before natural discovery during parsing.