Slow load data from LoadingController REST API Wordpress

Ionic Framework ionic-v3
1 
 
export class HomePage {
 
  loop: true;
 
  autoplayDisableOnInteraction: true;
 

  loader: Loading;

  posts: Observable<Post[]>;
  @ViewChild('pSlides') pSlides: Slides;
  constructor(public navCtrl: NavController, public wpProvider: WpProvider, public loadingCtrl: LoadingController, public toastCtrl: ToastController) {
    this.presentLoading()
    this.posts = this.wpProvider.getPosts();
    this.posts.subscribe(data => 
        this.loader.dismiss());

 
    }

can any one tell me what the wrong with this code

because I think it make my homepage very slow

this is an app for api wordpress posts

but when I open any post from home page the post is going fast