... to serve the React app. This gives us server-side rendering, routing, bundle splitting, hot reloading, and much more. However, in development when you visit a page it must first be loaded from the file system and transpiled and bundled by the server, served to the client, and then executed. This means there can be a small delay when loading a web page for the first time in development. In production, this delay should be vastly smaller, and can be eliminated with pre-fetching.