How to enable production mode in React?

You should use Webpack's DefinePlugin method to set NODE_ENV to production, by which it strip out things like propType validation and extra warnings. Apart from this, if you minify the code, for example, Uglify's dead-code elimination to strip out development only code and comments, it will drastically reduce the size of your bundle.

Practical Code Example

// In Vite / Webpack / Next.js: Set NODE_ENV to 'production'
// vite.config.js:
export default {
  define: {
    'process.env.NODE_ENV': JSON.stringify('production')
  }
};
// Eliminates development warnings and strips debug checks for maximum speed!