Angular 15: Handling Nested Observables with Async Pipe in Template and Performance Issues
I'm confused about I need help solving Quick question that's been bugging me - I'm facing a performance bottleneck when using the async pipe with nested observables in my Angular 15 application... I have a component that fetches user data and their associated posts from different endpoints. I'm using RxJS to combine these observables, but the rendering gets slow when the data set is large. The async pipe works fine for individual observables, but I'm running into trouble when trying to nest them like this: ```typescript import { Component, OnInit } from '@angular/core'; import { forkJoin } from 'rxjs'; import { UserService } from './user.service'; import { PostService } from './post.service'; @Component({ selector: 'app-user-posts', templateUrl: './user-posts.component.html' }) export class UserPostsComponent implements OnInit { userPosts$; constructor(private userService: UserService, private postService: PostService) {} ngOnInit() { this.userPosts$ = this.userService.getUsers().pipe( switchMap(users => { const postsRequest = users.map(user => this.postService.getPostsByUser(user.id)); return forkJoin(postsRequest).pipe( map(posts => users.map((user, index) => ({ ...user, posts: posts[index] })))); }); }) ); } } ``` In my template, I am using the async pipe like this: ```html <div *ngFor="let userPost of userPosts$ | async"> <h3>{{ userPost.name }}</h3> <ul> <li *ngFor="let post of userPost.posts">{{ post.title }}</li> </ul> </div> ``` While this works, it seems that as the number of users increases, the rendering time increases significantly. I've also noticed that if I try to console log the output from `userPosts$`, it takes noticeably longer to resolve with more users. I've tried using `mergeMap` instead of `switchMap`, but that didn't help improve performance. Also, I’ve considered using a caching mechanism, but I’m not sure how to implement that correctly here without complicating things. Is there a more efficient way to handle this scenario, or perhaps I’m missing some optimization techniques to make the data retrieval and rendering faster? This is part of a larger CLI tool I'm building. Am I missing something obvious? This is part of a larger application I'm building. What am I doing wrong?