Performance — does Hyvä really matter for fashion?

For fashion, more than any other vertical. Three reasons:

• PDPs are image-heavy — 8–15 product photos per PDP is normal in fashion. Luma + jQuery + RequireJS load all of them eagerly, killing LCP. Hyvä uses native lazy-load + Tailwind aspect-ratio classes + responsive image srcset, holding LCP under 1.5s on mobile.
• Variant pickers re-render on every interaction — size click → color update → fit update. Luma re-runs the full PDP JS on each click (200–400ms INP). Hyvä uses Alpine.js reactive state (under 80ms INP). At 50,000 variant catalogs the difference is the customer giving up vs. completing the purchase.
• Mobile traffic is 70–80% of fashion ecom. Core Web Vitals on mobile are non-negotiable for organic ranking on fashion head terms (e.g. “summer dresses” “men’s sneakers”).

Numbers from a recent Luma → Hyvä migration on a 12k-SKU women’s apparel store: Lighthouse mobile 42 → 96, LCP 4.1s → 1.3s, INP 320ms → 75ms. Measured conversion lift: +18% on mobile, +11% on desktop. Migration timeline: 6 weeks. ROI inside 90 days.

If you’re on Luma + 3 fashion-heavy apps and serious about ranking on category head terms, Hyvä migration is the highest-leverage spend you can make.