Ionic 4 slow on Viewsonic Ultra HD 4K

Please help me

Sorry if i post to wrong category.

I build android app with ionic 4. But when i install on Viewsonic device(model IFP 5550), the app run so slow. On my mobile the app run fine. At the first page of my app, it call api 2 time and after that don’t call any request to server. The loading popup duration is 2 seconds, but it show over 2 seconds before close.

My project will fail if i can’t solve thì problem.

This is my app:
And this is video demo on Viewsonic device: