AdminPageLoader.js

import React from 'react';

class AdminPageLoader extends React.PureComponent {
  constructor(props) {
    super(props);

    this.state = {
      AdminPage: null,
    }
  }

  componentDidMount() {
    import('./AdminPage').then(module => {
      this.setState({ AdminPage: module.default });
    });
  }

  render() {
    const { AdminPage } = this.state;

    return AdminPage
      ? <AdminPage {...this.props} />
      : <div>Loading...</div>;
  }
}

export default AdminPageLoader;