Migrating a legacy React app from webpack to Vite

A legacy React app was migrated from webpack 4 to Vite, delivering major speed gains across development and CI.

Dev server startup dropped from 42 seconds to 1.1 seconds, and hot module reload improved from seconds to milliseconds.

Production builds became faster, and CI deploy time fell from 14 minutes to 5 minutes.

The move took about three weeks because it also required upgrading React, React Router, the test runner, and other dependencies.