Nextjs 13 is insanely slow in dev environment

Question

I will be very brief:

I recently switched to Nextjs 13 and I noticed it's insanely slow when I run my app on localhost via npm run dev

Pages even take 10 seconds and sometimes even longer to load, how it is possible?

To all who use Nextjs: do you know if it's a problem of the new version 13? did you encounter the same problem?

Answer 1

I had a similar issue on a big project, and for that particular issue using swc seems to have reduced the compile time for the first time a route is accessed:

const nextConfig = {
// ...
    swcMinify: true,
//...
}

There is an ongoing issue on GitHub about it, people are suggesting what have work for their particular issue.

Answer 2

You can do the following things to speedup dev environment of Next.js 13+ development server.

Add the following item in next.config.js file.

module.exports = {
    fastRefresh: true,
};

You can add the following if above thing did not work in next.config.js.

module.exports = {
    concurrentFeatures: true,
};

Optimize the build configuration: Ensure that your build configuration is optimized for development. For example, you can disable certain optimizations like minification and source-maps to improve build speed during development. Review your next.config.js file and make appropriate adjustments.

Example is here in next.config.js:

module.exports = {
    productionBrowserSourceMaps: false, // Disable source maps in development
    optimizeFonts: false, // Disable font optimization
    minify: false, // Disable minification
};