title: Angular 8 - nested ngFor is extremely slow
body: <p>I am trying to display 2d array by 2 nested ngFor</p>
  
  <pre><code>&lt;div class="row" *ngIf="!calculating" style="margin: auto;"&gt;
      &lt;div class="col-xs-12 col-sm-12 col-md-12 col-sm-offset-1 col-md-offset-2"&gt;
        &lt;div class="row" *ngFor="let pixelRow of pixels" style="width: max-content;"&gt;
          &lt;div class="col pixel" 
          *ngFor="let pixel of pixelRow"  
          [ngStyle]="{'background-color': pixel.Color }"
          (click)="changePixelState(pixel.xIndex, pixel.yIndex)"&gt;&lt;/div&gt;
        &lt;/div&gt;
      &lt;/div&gt;
    &lt;/div&gt;
  </code></pre>
  
  <p>Basically it works fine on normal scale of data, but when it been defined as 1000X1000 - It takes huge time to be display and meanwhile the page is not responsive.
  I have tried to use cdk-virtual-scroll-viewport but i couldn't find any documentation of how to use it on 2d array, only on one list of data.</p>
  
  <p>What can I do? any Ideas?</p>