How we reduced the size of our JavaScript bundles by 33%

This post details the migration from a custom, legacy module bundler to Rollup. It explains the problems with the old system, including manual code-splitting, lack of tree-shaking, and multiple versions of bundled code. The adoption of Rollup is justified by its maturity and flexibility. The rollout process is described in four stages: developer preview, Dropboxer preview, general availability, and a gradual rollout to production. The post emphasizes the benefits of automatic code-splitting and tree-shaking in reducing JavaScript bundle sizes and improving web performance.