Ionic 4 app is slow in android 7.1

Hi, I am developing an app ionic 4 with angular 7. It runs pretty good in desktop Chrome or android device with latest configuration (4gb ram, 32gb storage, android version 8/9). When I packaged it and installed in android device(2gb ram, 8gb storage, android version 7.1), It runs too slowly. for example: if you open a modal/popup in latest config device, it takes 1000-1500ms whereas in another device it is taking 4000-6000ms.
Cordova uses android’s Web view to run the applicaiton, the bad performance is due to default browser?
In old device the chromium version installed in 66.
if anyone have any suggestion, it is much appreciated. thanks in advance