Explore the challenges and solutions encountered during Etsy's migration to Webpack in this JSConf US 2019 talk. Discover how to integrate a modern JavaScript build system into a large, legacy codebase without running out of memory. Learn strategies for localizing JavaScript into multiple languages efficiently and understand the impact of seemingly small performance issues on large-scale deployments. Gain insights into overcoming obstacles when transitioning from an in-house build system to Webpack, including memory management, language localization, and critical performance optimizations.