E-Commerce Migration: 40% Faster Load Times

An established online retailer with $5M+ annual revenue was losing customers to faster competitors. Their 8-year-old PHP monolith had accumulated technical debt that made every change risky and slow. Page load times averaged 4.8 seconds on mobile, their Google PageSpeed score was 34/100, and their mobile conversion rate was 60% lower than desktop. The business could not afford a 6-month freeze for a complete rewrite. They needed a migration strategy that improved performance immediately while allowing the business to continue operating and shipping features.

We implemented a strangler fig migration pattern — gradually replacing the legacy system piece by piece rather than a big-bang rewrite: 1. Phase 1 (Weeks 1-3): New Next.js frontend deployed alongside the legacy PHP backend. Product listing pages and search were the first to migrate, using the existing PHP API as a data source. Immediate 50% improvement in page load times for migrated pages. 2. Phase 2 (Weeks 4-6): Product detail pages, cart, and checkout migrated. We implemented edge caching with Cloudflare for product images and static assets. Added lazy loading, image optimization via Next.js Image component, and code splitting. 3. Phase 3 (Weeks 7-10): Backend API migrated from PHP to Node.js with Express. Database optimized — added proper indexes, implemented Redis caching for frequently accessed products, and set up CDN for all static assets. Key technical wins: Server-side rendering for SEO (critical for product pages), optimistic UI updates for cart operations, prefetching of likely next pages, and a service worker for offline product browsing.

The migration completed in 10 weeks with zero downtime: • Average page load time dropped from 4.8s to 2.9s (40% improvement) • Mobile PageSpeed score improved from 34 to 95 • Mobile conversion rate increased by 25% • Overall revenue increased by 18% in the first quarter post-migration • Core Web Vitals all passed to "Good" threshold • Time to deploy new features reduced from 2 weeks to 2 days • Server costs decreased by 30% due to efficient caching and the switch from PHP-FPM to Node.js The client has since expanded into two new markets using the same platform, which would have been impossible with the legacy architecture.