Adaptive skill practice — find your level, get sharper.

Web Performance practice

Make pages fast — Core Web Vitals and what actually moves them

Web performance the way interviews and real audits demand it — the Core Web Vitals (LCP, CLS, INP) and their decomposition, the critical rendering path, loading strategy (defer/async, preload and priorities, lazy loading done right), HTTP caching semantics (max-age vs no-cache vs immutable, CDN vs browser split), image and font optimization, JavaScript cost (long tasks, code splitting, hydration), rendering performance (layout thrashing, compositor animations), and measurement discipline (lab vs field, percentiles, attribution). Grounded in web.dev, MDN, and the HTTP specs. Part of the Developer track.

• Meets you at your level — never too easy, never too hard.

• Adapts every question to how you’re doing.

• Tracks your level over time. Skill practice, not a test.

New here? Read the Web Performance guide

A free 16-minute primer — the mental model, the mistakes beginners make, and what to practise first.

Curriculum

141 concepts across 19 chapters, from foundations through advanced practice — each one a concept the adaptive question bank can teach and test.

A. Why speed matters and what a good metric is

B. Largest Contentful Paint — what it measures

C. Diagnosing and fixing LCP

D. Cumulative Layout Shift — what it measures

E. Preventing layout shift

F. Interaction to Next Paint

G. Long tasks and the main thread

H. The cost of JavaScript

I. Script loading and third parties

J. The network path to the first byte

K. Resource hints and priority

L. Images and video

M. Web fonts

N. CSS and the critical rendering path

O. Rendering: frames, layout and compositing

P. HTTP caching, CDNs and the service worker

Q. Speculative loading and the back/forward cache

R. Measuring: APIs, lab and field

S. Budgets and regression discipline

View the full curriculum →

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