Incorrect (imports entire namespace):

import { tracked } from '@glimmer/tracking';
import Component from '@glimmer/component';
import { action } from '@ember/object';
// OK - these are already optimized

// But avoid this pattern with utility libraries:
import * as lodash from 'lodash';
import * as moment from 'moment';

class My extends Component {
  someMethod() {
    return lodash.debounce(this.handler, 300);
  }
}