EF Education First · 2023 – present
EF EPI
Making EF’s flagship data-visualisation site fast for every market it serves.
−60%page load time on a platform read by 3.4M people a month in 57 markets.
The project
The EF English Proficiency Index is the world’s largest ranking of countries and regions by English skills: a Next.js application serving 57 international markets.
- Role
- Senior Frontend Engineer · EF Education First
- Stack
- Next.js
- TypeScript
- Data visualisation
- Core Web Vitals
The problem
EF’s flagship data-visualisation site had grown slow. For a page whose job is to be read, shared and cited across 57 markets, load time was the product.
What I did
- Diagnosed the rendering and loading bottlenecks on the Next.js platform before changing anything.
- Re-architected the front end and its data layer around what those measurements showed.
- Tracked load time as a business metric across every market, not as a one-off audit.
What changed
Page load times fell by 60%, time to interactive improved by three seconds, and all three Core Web Vitals moved into better ranges.
Re-architected the EF EPI front end and its data layer; all three Core Web Vitals improved.
All of it at the scale of 3.4M monthly active users, 57 international markets and 17 production apps deployed daily.
