Dexie&Angular 4:选择项目时表现缓慢

表中最多只有20.000个项目,但选择这些项目需要几秒钟(在Chrome 61上为5秒,在iOS 10上为20秒以上);iOS 11)

下面是我的服务,它获取两个不同的表,并通过 loadItems()

@Injectable()
export class ItemService {

    private buildings: Dexie.Table<Building, string>;
    private people: Dexie.Table<Person, string>;

    private activeZip: string;

    constructor(
        private db: IndexeddbService,
    ) {
        this.buildings = this.db.table('buildings');
        this.people = this.db.table('people');
    }

    loadItems(): Observable<{
        buildings: Building[],
        people: Person[]
    }> {
        return Observable.combineLatest(
            this.loadBuildings(),
            this.loadPeople(),
        ).map(([buildings, people]) => {
            return {
                buildings,
                people
            };
        });
    }

    private loadBuildings(): Observable<Building[]> {
        return Observable.from(this.buildings.where('zip').equals(this.activeZip).toArray());
    }

    private loadPeople(): Observable<Person[]> {
        return Observable.from(this.people.where('zip').equals(this.activeZip).toArray());
    }
}

@Effect()
loadItems$: Observable<Action> = this.actions$
    .ofType(actions.ActionTypes.LOAD_ITEMS)
    .map(_ => this.itemService.setActiveZip(this.localStorageService.getActiveZip()))
    .switchMap(_ => this.itemService.loadItems())
    .map(items => new actions.LoadItemsSuccessAction(items))
    .catch(error => Observable.of(new actions.LoadItemsFailAction(error)));

我试着通过 https://github.com/raphinesse/dexie-batch ,但最终批次需要500多秒才能到达。

哪里可能存在性能瓶颈?我已经尝试在Angular的区域之外运行此查询,但这并没有带来性能改进。