Frontend
Performance
Making pages load fast and respond smoothly, measured by Core Web Vitals — LCP, CLS and INP. Levers include code-splitting, lazy loading, image optimisation, caching, cutting main-thread work and avoiding layout thrash. Speed directly affects conversion and SEO. The rule is to measure first with real tooling before optimising anything.
Purpose
Web performance is how fast a page loads and how smoothly it responds, measured today by Core Web Vitals: LCP (largest contentful paint — loading), CLS (cumulative layout shift — visual stability) and INP (interaction to next paint — responsiveness). It matters commercially: speed measurably moves conversion, retention and search ranking.
When to Use It
It deserves attention on anything user-facing, and becomes critical on mobile networks and low-end devices — the median user's reality. E-commerce and content sites feel it most directly in revenue and SEO.
Trade-offs
Optimisation adds complexity — code-splitting, caching layers, image pipelines — so spend it where measurements say it matters, not where intuition points. Synthetic lab scores and real-user field data can disagree; the field data is the truth.
Implementation
Measure first with Lighthouse and real-user monitoring. Then apply the standard levers: compress and properly size images, code-split and lazy-load below-the-fold work, preload critical fonts, cache aggressively with a CDN, keep the main thread free of long tasks, and reserve space for late-loading content so the layout never shifts.