Loading scenes extremely slow for android

Our game performance is good on IOS but horribly bad on Android.
Our biggest problem is switching scenes.
For IOS, switching scenes takes about 1 second and for a latest Android phone, its about 15s.

I wounder if anyone else had similar problem.

Version = 5.4.0p2

Thank you in advance for your kind input.

Did you used any image effects on camera ?

I did not, but I found the main problem is “Loading.ReadObjectThreaded”.
This thing alone is 5000+ ms