Start with the right triage order
Core Web Vitals measure real user experience: Largest Contentful Paint (LCP), Interaction to Next Paint (INP), and Cumulative Layout Shift (CLS). Fixing everything at once is slow. Triage by template: homepage, product/detail pages, and key landing pages first.
- Confirm which templates fail on mobile field data
- Reproduce with lab tools on the same URLs
- Separate media issues, script issues, and layout issues
- Ship one class of fix at a time and re-measure
LCP: make the main content appear faster
LCP often fails because the hero image, product image, or headline block is delayed by oversized media, late discovery, or blocked rendering.
- Compress and correctly size hero/product images
- Preload the true LCP image when it is known
- Reduce render-blocking CSS and fonts where possible
- Avoid lazy-loading the LCP element
INP: keep pages responsive to input
INP suffers when heavy JavaScript monopolizes the main thread. Third-party tags, theme scripts, and app embeds are frequent culprits on ecommerce and SaaS marketing sites.
- Defer non-critical scripts
- Audit tag managers and marketing pixels on key templates
- Break up long tasks in custom theme code
- Test mobile mid-tier devices, not only desktop
CLS: stop unexpected layout jumps
CLS usually comes from images or embeds without dimensions, late-loading fonts, and injected banners. Reserve space for known UI and avoid inserting content above existing content after load.
How Verify My Link helps
A performance checker scan helps you identify which pages need deeper Core Web Vitals work, while companion SEO and link checks catch related quality issues that often ship in the same release. For Shopify teams, start with the Shopify performance checker.