I was having really poor performance on my Android 9 device, what really improved the UX in my case was:
- use of *ngIf to reduce the dom size as much as possible
- improve image size/compression (with tinypng or similar)
- disable ionic animations with
IonicModule.forRoot({animated: false})
So the bottom line IMO is keep the dom as small as possible and avoid animations and/or big images.