gistfile1.js

// something like:
<BundleLink to="/profile" onLoadStart={() => {
  // throw a spinner up on the "old" page while we load
  this.setState({ navigating: true })
}}>Profile</BundleLink>

<BundleLink to="/dash" prefetch={true}>Dashboard</BundleLink>

///////////////////////////////////////////////////////
const BUNDLED_ROUTES = {
  '/profile': () => import('./Profile'),
  // etc.
}

class BundleLink {
  componentDidMount() {
    // could be smarter, do it as the mouse gets close,
    // or keyboard gets focus
    if (this.props.prefetch) {
      this.load()
    }
  }

  handleClick(e) {
    // check if right click, defaultPrevented, etc. first
    this.load()
  }

  load() {
    const { to, history, onLoad } = this.props
    onLoadStart()
    BUNDLED_ROUTES[to]().then(() => {
      history.push(to)
    })
  }

  render() {
    const { history, match, onLoad, location, ...props } = this.props
    return (
      <Link {...props} onClick={this.handleClick}/>
    )
  }
}

export default withRouter(BundleLink)
///////////////////////////////////////