High CPU usage while running on OS X

After running npm start, the node process consumes ~40% CPU on my machine:

I found that setting a polling interval in the the WebpackDevServer helped:

new WebpackDevServer(compiler, {
    historyApiFallback: true,
    hot: true, // Note: only CSS is currently hot reloaded
    publicPath: config.output.publicPath,
    quiet: true,

    // added this:
    watchOptions: {
      poll: 1000
    }
  })

Here were the settings I tried, and the resulting CPU usage:

poll: 1000  =>  4-6% CPU
poll: 500   =>  8-10% CPU
poll: 250   =>  14-16% CPU

There’s a tradeoff between CPU usage and how snappy the dev experience feels. To me, 1000ms felt sluggish, but 500ms felt pretty good. I couldn’t discern much difference between 500ms and 250ms.

It seems like adding some kind of polling interval would be a good idea to reduce the CPU usage.

[gaearon]

Closing then. If you’re having issues, try:

1. Removing node_modules
2. Updating react-scripts to the latest version in package.json (make sure you follow the migration instructions in changelog for every release you’re skipping)
3. Updating npm (npm i -g npm@latest) or Yarn (yarn self-update)
4. Running npm install (or yarn)

[ggregoire]

Can confirm here.

I updated from node 6.8.1 to node 7.1.0 yesterday and now the node process consumes 100% CPU on my machine.

I didn’t find anything relative to CPU usage and node 7 in Webpack issues.

I’m on El Capitan + latest version of CRA.

@gaearon @dceddia Should we reopen the issue or create a new one?

Edit: For those who have the same problem, you can downgrade with brew switch node x.x.x and list all the versions installed with brew info node.