How fast should my Shopify store load?

Google's Core Web Vitals are the canonical performance benchmark and the same numbers Google uses for ranking. The targets are: LCP (Largest Contentful Paint) under 2.5 seconds, CLS (Cumulative Layout Shift) under 0.1, INP (Interaction to Next Paint) under 200 milliseconds. "Good" thresholds apply at the 75th percentile, meaning 75% of real-user sessions need to hit them, not just lab tests.

The 7%-per-second number is the most-cited stat and it is approximately right. Shopify's internal research, plus Google's 2018 mobile-speed study, plus Walmart's 2012 study, all triangulate to roughly the same conversion drag: each additional second of perceived load time costs 5-8% of conversions. On a 1.4% CVR baseline, going from 2.5s to 4.5s LCP roughly halves your conversion rate.

On Shopify specifically, the dominant cause of slow LCP is third-party app scripts. Every app you install injects script tags that block render. Stores running 8+ apps frequently push LCP past 4 seconds without realising it. Audit installed apps quarterly: any app whose conversion lift you cannot specifically measure should be removed.

The second biggest cause is unoptimised hero imagery. A 2MB JPEG hero image on a slow connection can swallow 2-3 seconds of LCP by itself. Use Shopify's built-in image optimisation (img_url with width parameter) and serve WebP or AVIF where supported. The hero image should be under 200KB and dimensioned to the actual rendered size, not the raw upload.

Theme matters but matters less than apps. Modern Shopify themes (Dawn, Sense, Crave) are reasonably fast out of the box; older themes (Brooklyn, Debut, Narrative) skew slower but the difference is rarely the dominant factor. Migrating themes is high-effort/low-leverage compared to pruning apps and optimising images.