stability testing of Cesium app on mobile devices

After testing my sample app on many mobile devices (Android and iOS)
and web browsers, I conclude the following observations for reference:

(The tested web site: http://210.241.90.223/apps/demo.html)

  1.  Android
    

v.s. iOS:

(1) Android
devices:

All devices work fine.

(2) iOS
devices:

a. device on Landscape mode:

all devices work fine.

b. device on Portrait mode:

(a) normal
screen mode: error occurred(or unstable) on all iOS devices.

(b) full screen mode: all
devices work fine.

  1.  Performance
    

on rendering the OSM base map

devices on
Landscape mode get better performance than that on Portrait mode.

  1.  bgltf v.s.
    

gltf

(1) gltf:
stable on mobile device and web browser.

http://210.241.90.223/apps/demo2.html

(2) bgltf: unstable on mobile
device, but stable on web browser.

http://210.241.90.223/apps/3DNavEn.html