Digital Commerce — High-Performance E-Commerce Migration

The Context

A Nantes-based e-commerce client with a solid physical business was experiencing an anomaly: thousands of visitors per month on their site, but an online conversion rate of only 0.4%. The industry average is 2–3%.

The site ran on WordPress + WooCommerce with 43 active plugins. The first seconds of loading kept the browser at 100% capacity — leaving visitors staring at a white screen.

The Challenge

Migrate an e-commerce site without interrupting sales, without losing acquired SEO rankings, and without breaking existing integrations (payment, inventory, transactional emails).

Additional constraints:

• Preserve all existing product URLs (301 redirects on the few changes)
• Maintain real-time inventory sync
• Deliver within six weeks

Our Approach

We chose a headless architecture: Shopify manages the catalog and inventory as a backend; Next.js handles all rendering on the front end.

Static generation + ISR. Product pages are pre-generated at build time and automatically regenerated on each stock update. Visitors receive a complete HTML page within tens of milliseconds.

Systematic image optimization. Product visuals — previously unresized 3–4 MB JPEGs — are now served as WebP at the correct resolution via next/image. 70% reduction in total page weight.

Removing render-blocking resources. Fonts, Facebook pixel, live chat — all loading synchronously on the old site. Now deferred until after the first visible render.

The Result

Six weeks of migration. Zero service interruption.

LCP dropped from 6.2 seconds to 0.9 seconds. Mobile Lighthouse score jumped from 31 to 94. Conversion rate doubled over six weeks — as Google updated its rankings and the user experience improved. Online revenue grew 127% in the three months following launch.

A fast website isn't just "pleasant" — it's a direct business variable.