Frontend Performance and Rendering Optimization Questions

Making web pages and single-page apps fast: Core Web Vitals (LCP, INP, CLS) and page-speed metrics, the critical rendering path, reflow, repaint, forced synchronous layout and compositing, and diagnosing loading and rendering bottlenecks with browser DevTools, long-task traces and field data. Covers bundle size, code splitting, tree shaking and lazy loading, JavaScript parse and compile cost, script loading (async, defer), resource hints and fetch priority, HTTP/2 and HTTP/3 loading trade-offs, image and web-font delivery, critical CSS, a page's own browser caching (Cache-Control, fingerprinted filenames) and service-worker caching of a web app's assets, offloading work to Web Workers, smooth animation on the compositor, list virtualization and React re-render optimization, browser memory leaks and garbage-collection jank, third-party script impact, loading WebAssembly modules, rendering-strategy trade-offs for speed (CSR, SSR, SSG, streaming and partial hydration), and measuring and defending speed: user timing, real user monitoring against synthetic tests, performance budgets in CI, regression investigation and performance targets across teams. Server-side and system latency, CDN and edge caching, distributed caches, general state-management design, and design-system or visual-design decisions are covered elsewhere.