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Storefront performance

Always-on rule for storefront-performance  ·  Source

  • Judge Core Web Vitals on field data at the 75th percentile, mobile and desktop apart.
  • Good means LCP at most 2500 ms, INP at most 200 ms, CLS at most 0.1.
  • Never lazy-load the main product image. Give it fetchpriority="high" and the right size.
  • Set image dimensions and reserve space for banners and widgets.
  • Break up long tasks and defer third-party scripts.
  • Cache catalog pages for anonymous shoppers only. Bypass cart, checkout, account, and session cookies.
  • Purge cached pages when price or stock changes.
  • Recheck field data over 28 days after a change.