Optimizing JavaScript Bundle Size: The Hidden Performance Crisis Affecting Every App

JavaScript bundle size is not an abstract metric—a 2MB gzipped bundle takes 12 seconds to parse on mid-range Android devices over 3G before any interaction is possible. Bundle bloat accumulates silently through everyday imports (moment.js locales, full lodash, oversized icon libraries), degrading performance on devices developers never test on. Mastering tree shaking and code splitting is essential for delivering responsive applications across the entire spectrum of real-world hardware.