Rspack Best Practices

This is a configuration and optimization guide for Rspack, the Rust-powered bundler that's becoming a faster alternative to webpack. It covers the essentials: setting up rspack.config.ts with defineConfig, choosing between built-in CSS handling versus legacy loaders for webpack migrations, and profiling bottlenecks with RSPACK_PROFILE or Node's cpu-prof flag. The real value is in the opinionated choices, like preferring Rspack's built-in plugins over JavaScript alternatives and keeping rule conditions explicit. Use this when you're starting a new Rspack project, migrating from webpack, or troubleshooting slow builds. The guidance on asset modules versus legacy loaders and the security note about not publishing source maps are especially practical.