audit-bundle-size — Find and Eliminate Bundle Bloat

Every kilobyte of JavaScript the browser must download, parse, and compile before showing anything costs real users real time. A large initial bundle is the #1 avoidable cause of slow LCP and poor Core Web Vitals. This skill finds exactly what is bloating it and tells you how to fix each item.

Phase 0: Detect bundler and existing setup

package.json scripts.build   → build command and framework
vite.config.*                → Vite + rollupOptions
next.config.*                → Next.js (webpack / Turbopack)
webpack.config.*             → standalone Webpack
astro.config.*               → Astro (islands, Vite underneath)