[1971] How to debug nuxt/webpack/loaders?

Since our project grew up dev build process (nuxt) became super-slow. We are waiting like 30s-1m for hot reload, no matter if we change one of the components template or just scss (we keep scss separately and include it through nuxt.config.js "css" options).

I want to investigate where webpack/nuxt spends so much time when rebuilding app. My question is how to output in console (or file?) what is webpack/nuxt actually doing when I change something in app source code. I tried following in nuxt.config.js (found in webpack docs):

extend (config, ctx) {
  config.plugins.push(new webpack.LoaderOptionsPlugin({
    debug: true
  }))
  config.stats = 'verbose'
}

But it does not output any extra info - are those config options overwritten by nuxt? Are there any other options of debugging what is webpack actually doing?

Using nuxt@1.0.0-rc11