Slow production builds, sometimes upwards of 60 seconds

[tamj0rd2]

We're using nextjs and when building for production, the command can take up to a minute. I'm not sure what the first steps to debug this issue are. Could anyone give me some pointers please? Here are a couple of config files in case they might help:

tsconfig.json:

{
  "compilerOptions": {
    "target": "esnext",
    "module": "esnext",
    "jsx": "preserve",
    "lib": ["dom", "es2019"],
    "baseUrl": ".",
    "rootDir": "src",
    "moduleResolution": "node",
    "strict": true,
    "allowJs": false,
    "noEmit": true,
    "allowSyntheticDefaultImports": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "isolatedModules": true,
    "removeComments": false,
    "preserveConstEnums": true,
    "sourceMap": true,
    "forceConsistentCasingInFileNames": true,
    "resolveJsonModule": true,
    "typeRoots": ["./types", "./node_modules/@types"],
    "paths": {
      "~shared": ["./src/shared/index"],
      "~shared/*": ["./src/shared/*"],
      "~client/*": ["./src/client/*"]
    }
  },
  "references": [
    {
      "path": "./src/shared/tsconfig.json"
    }
  ],
  "include": ["next-env.d.ts", "src/pages/**/*", "src/client/**/*", "types/ResizeObserver.d.ts"],
  "exclude": ["dist", ".next", "dist", "next.config.js", "node_modules/**/*"]
}

next.config.js

const path = require('path')

const webpackConfig = (config, { isServer, defaultLoaders }) => {
  if (!isServer) {
    config.module.rules.push({
      test: /\.js$/,
      include: [],
      use: [defaultLoaders.babel],
    })

    config.module.rules.push({
      test: /\.(js|tsx|ts)?$/,
      include: [path.join(process.cwd(), 'node_modules/swr')],
      use: [defaultLoaders.babel],
    })
  }
  return config
}

module.exports = {
  distDir: './dist',
  serverRuntimeConfig: {},
  publicRuntimeConfig: {},
  webpack: webpackConfig,
  poweredByHeader: false,
}