Web Performance

v1.0.0

Reviews front-end code for performance — Core Web Vitals, lazy loading, image optimization, bundle size, and rendering efficiency. Performance directly impacts conversion rates and search rankings, but degradation happens gradually and is easy to miss in development.

3 rules

1 categories

Performance(3)

Lazy-Load Below-Fold Content

Lazy-load images, components, and data that are below the initial viewport fold. Loading everything upfront makes the user wait for content they haven't scrolled to yet — increasing Time to Interactive and burning mobile data on content the user may never see.

Web PerformanceperformanceLazy Loading

HIGH

Automate Web Performance checks on every PR

BeforeMerge scans your pull requests against all 3 Web Performance rules automatically. Get actionable feedback before code ships.

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Web Performance Review

A review skill that catches front-end performance regressions before they reach users.

What it covers

Core Web Vitals — LCP optimization, CLS prevention, INP/FID reduction strategies
Bundle size — tree-shaking effectiveness, code splitting boundaries, dynamic imports for heavy modules
Image optimization — modern formats (WebP/AVIF), responsive srcset, lazy loading below the fold
Rendering — avoiding layout thrashing, requestAnimationFrame for visual updates, virtualization for long lists
Network — resource hints (preload/prefetch), HTTP caching headers, minimizing waterfall chains
JavaScript cost — main thread blocking, Web Worker offloading, avoiding synchronous heavy computation

When to use

Run this on PRs that add new dependencies, modify page layouts, or change data-fetching patterns. Essential before major launches where performance directly affects business metrics.