How We Made Carousell's Mobile Web Experience 3x Faster
Article Summary
Stacey Tay from Carousell reveals how her team achieved a 3x speed improvement on mobile web—and turned it into a 63% traffic surge. The secret? A ruthless performance budget and smart PWA architecture.
Carousell, a Southeast Asian classifieds marketplace, faced a critical challenge: their mobile web took over 15 seconds to load on 3G networks in Indonesia and the Philippines. The team spent 6 months building a performance-first Progressive Web App to serve users with slower devices and unreliable internet.
Key Takeaways
- Set strict 120KB budget for critical resources, 2s First Contentful Paint limit
- Route-based code splitting plus service workers reduced repeat load times dramatically
- 63% organic traffic increase in Indonesia, 3x boost in ad click-throughs
- Flow typing and design system enabled fast iteration without breaking things
- Automated bundlesize checks in PRs enforced performance budget religiously
By implementing a performance budget and PWA best practices, Carousell cut mobile web load time by 67% and saw immediate gains in user engagement and conversions.
About This Article
Carousell's mobile web took over 15 seconds to load on 3G networks in Indonesia and the Philippines. Their Lighthouse performance score exposed real optimization gaps as they tried to expand beyond Singapore's faster markets.
The team split code by route and used Workbox to precache assets. They inlined critical CSS with mini-css-extract-plugin, lazy-loaded images with scroll observers, and set a 120KB budget for critical resources. Automated bundlesize checks enforced this limit on every PR.
The listing page loaded 3x faster. Organic traffic from Indonesia jumped 63%, ad click-through rates tripled, and 46% more anonymous users started chats on listings. All this happened within three weeks of launch.