Downgraded Angular component slows down application

I have an angular-Application running in hybrid-mode. For this application I wrote an Angular2-Component, which I am downgrading to angularJS. This new component is used very often in the project.

Basically it is working, however the CPU load of the application is extremly high now. It feels notably slower.
If I remove more and more <custom-icon> it uses less CPU and feels faster again.
Now I am wondering what could be the reason for this?

Here is my symplified code:

app.module.ts

const ng1IconComponent = downgradeComponent({ component: IconComponent }) as angular.IDirectiveFactory;

@NgModule({
    imports: [
        BrowserModule,
        HttpClientModule,
        FormsModule,
        SharedModule,
        TranslateModule,
        CoreModule,
        FieldsModule,
        FiltersModule,
        ModalsModule,
        MiscModule,
        MainModule,
        ViewsModule,
        CustomRouterModule,
        FontAwesomeModule,
    ],
    providers: [{ provide: LOCALE_ID, useValue: 'de-DE' }],
    exports: [],
    declarations: [ServiceBootstrapComponent, IconComponent ],
    entryComponents: [ServiceBootstrapComponent, IconComponent ],
})

// Register in NG1
app.directive('customIcon', ng1IconComponent );

Customicon.component.ts

import { Component, OnInit, OnChanges, OnDestroy, Input } from '@angular/core';

@Component({
    selector: 'custom-icon',
    templateUrl: './customicon.component.html',
})
export class CustomIconComponent implements OnInit, OnChanges, OnDestroy {

    // bindings:
    @Input() iconset: 'fas' | 'far' | 'fal' | 'fab' | 'glyphicon';
    @Input() icon: string;

    ngOnInit() {}
    ngOnChanges() {}
    ngOnDestroy() {}
}

Customicon.component.html

<fa-icon *ngIf="(iconset) !== 'glyphicon'" [icon]="[(iconset), (icon)]" class="{{iconClass}}"></fa-icon>

<i *ngIf="(iconset) === 'glyphicon'" class="glyphicon" [ngClass]="(icon)"></i>

An example-call (mostly from an ng1-component) would be:

<custom-icon iconset="glyphicon" icon="{{$ctrl.selected ? 'glyphicon-check' : 'glyphicon-unchecked'}}"></custom-icon>

Screenshots:

Open a Dropdown with downgraded “custom-Icons”-component:
enter image description here

Open a Dropdown without downgraded “custom-Icons”-component:
enter image description here

Source: AngularJS