Can Hyvä improve Core Web Vitals on Magento 2?

On most stores, yes, for LCP and CLS within 28 days of launch, and for INP almost immediately. The exception is stores with severe TTFB problems (above 1s) or heavy third-party tag stacks. Those need a separate sprint.

CrUX uses a 28-day rolling window. You will see real-user field data shift within 14 days of launch and stabilise by day 28. Synthetic lab tools (Lighthouse, PageSpeed Insights) show the improvement instantly.

Both, but the desktop delta is smaller. Luma desktop LCP is often already 2-3s; Hyvä trims it to 0.8-1.5s. Mobile is where the dramatic 5-10s → 1.5-3s shift happens, because mobile is CPU-bound, not bandwidth-bound.

Backend-only extensions (shipping, payment, ERP sync) port over with zero changes. Frontend extensions with Knockout/RequireJS templates need a Hyvä-compatible variant, a Hyvä compatibility module, or a fallback layer. Check the Hyvä compatibility checker before migration.

Yes, Hyvä supports Magento 2.4.4-2.4.9 and PHP 8.1-8.4. The Hyvä team ships compatibility updates within days of each new Magento release.

INP measures the latency of the slowest interaction during a page view. Luma's slowest interaction is almost always the mini-cart update (Knockout customer-data round-trip), which on a mid-range Android takes 400-800ms. Hyvä's Alpine.js-driven mini-cart updates in 80-200ms. That single change usually moves a store from "Poor" to "Good" on INP.

Almost none, but watch for: late-injected GTM banners (cookie consent), customer-data sections in custom-built header components, and any third-party widget that injects DOM after first paint. All three are fixable with explicit space reservations.

Indirectly. Core Web Vitals is a confirmed Google ranking signal. Going from "Poor" to "Good" on mobile CWV won't 10x your rankings overnight, but it removes a tiebreaker penalty and usually surfaces a 5-15% organic uplift over 60-90 days. Combined with the technical SEO win from Magento vs Shopify on schema and hreflang, the compounding effect is real.

Yes. Hyvä installs in a sibling theme slot, so you can route a percentage of traffic to it via Cloudflare Workers or a load balancer. Most migrations I run start with a 10% canary for two weeks before the full cutover.

A clean Luma→Hyvä migration on a standard catalog (50-500 SKUs, 5-10 custom modules, standard checkout) runs roughly ~80h @ $25/hr. Stores with heavy frontend customisations or a checkout extension stack can go to 120-160h. Fixed-fee sprint starts at $2,499.

Google PageSpeed Insights pulls the same CrUX field data Search Console uses. Search Console → Experience → Core Web Vitals also charts the 28-day trend. CrUX BigQuery dataset is the deepest source.