Angular 16 - Issues with Change Detection in ngFor with Async Pipe and TrackBy Function
I've looked through the documentation and I'm still confused about I'm deploying to production and I'm facing a performance issue in my Angular 16 application when using `ngFor` to render a list of items with an async pipe. I have a service that fetches data from an API, and I'm using the async pipe to directly bind the observable to the template. However, I noticed that even with the `trackBy` function, the entire list seems to be re-rendered every time the observable emits a new value, causing noticeable lag in the UI. Here's a simplified version of my code: ```typescript // my-service.ts import { Injectable } from '@angular/core'; import { HttpClient } from '@angular/common/http'; import { Observable } from 'rxjs'; @Injectable({ providedIn: 'root' }) export class MyService { constructor(private http: HttpClient) {} fetchItems(): Observable<Item[]> { return this.http.get<Item[]>('https://api.example.com/items'); } } ``` ```typescript // my-component.ts import { Component, OnInit } from '@angular/core'; import { MyService } from './my-service'; import { Observable } from 'rxjs'; @Component({ selector: 'app-my-component', templateUrl: './my-component.html' }) export class MyComponent implements OnInit { items$: Observable<Item[]>; constructor(private myService: MyService) {} ngOnInit() { this.items$ = this.myService.fetchItems(); } trackById(index: number, item: Item): number { return item.id; } } ``` ```html <!-- my-component.html --> <ul> <li *ngFor="let item of items$ | async; trackBy: trackById">{{ item.name }}</li> </ul> ``` Despite implementing `trackBy`, the performance is still suboptimal. I expected that only the changed items would re-render, but it seems like Angular is still treating the entire list as changed. I've checked that the `id` property is unique for each item and that there are no other directives in the template that could trigger additional change detection cycles. I also ensured that the observable doesn't emit the same array reference. I've tried using `ChangeDetectionStrategy.OnPush` in my component but it didn’t resolve the issue either. Is there something I'm missing or a better approach to handle this situation? I'm on macOS using the latest version of Typescript. I'm developing on Ubuntu 22.04 with Typescript. Thanks for any help you can provide!