First things, I would have a look to the popovers. Double check your lifecycles (ngOnInit, ionViewWillEnter etc.) to see if there isn’t something which takes too much time to load from your app?
Maybe even to move code from a lifecycle to another (like something from ionViewWillEnter to ionViewDidEnter too. That might improve the UX.
If nothing work, yes with Angular it’s possible to preload only one or multiple selected modules, see following articles.
But first I would suggest to have a look and play with the lifecycles.