Headless store with 0.8 s LCP and +28% conversion

The label had sold through a standard Shopify theme for 3 years. Every new wish became an app: reviews, bundles, size advice, pop-ups, pixels. 14 apps later, the product page loaded in 3.1 seconds on mobile (LCP), Lighthouse scored 41, and organic visibility slid a little further every quarter. Ad costs went up; conversion did not.

Because it is our own label, we knew the numbers exactly and could make hard calls without stakeholder rounds. The question was not whether the store could be faster, but whether a headless setup pays for itself for a label with 400 SKUs and 2 collections a year. We decided to measure it rather than estimate it.

We kept Shopify as the backend for products, inventory, checkout and payments, and built the storefront in Hydrogen on the Storefront API. Content (lookbooks, size guides, collection stories) moved to Sanity so marketing can publish without a deploy. Hosting on Cloudflare with edge caching per country.

Of the 14 apps, 3 survived, as API integrations instead of scripts on the page: Klaviyo for email and flows, Sendcloud for shipping and returns, and server-side GTM for measurement with Consent Mode v2. Reviews, bundles and size advice we built ourselves. That cost 2 extra weeks and saves licenses and 900 kilobytes of JavaScript every month.

The migration ran for 9 weeks alongside the existing store. In week 8 an A/B test sent 50% of traffic to the new storefront: same products, prices and campaigns. Only when the conversion gap had held steady for 3 weeks did we switch to 100% and delete the theme.

The new store loads the product page in 0.8 seconds on an average phone, with AVIF images, color and size selection without a reload, and a checkout that Shopify continues to handle. Size advice uses the label's own returns data: per product it shows which size customers of the same height kept.

For SEO, every category received its own copy block and structured data from Sanity, and 1,800 duplicate URLs from the old theme disappeared. Speed plus clean indexing delivered 34% more organic sessions within 4 months, on top of the higher conversion.