The app is running slow in andorid

I built a xamarin app which is running fine in iOS. That is quite smooth. However, after I ported Android, that is very slow, specially, I use Navigation.PushAsync(new Page());
I tried to link all assemblies, but I got this exception : argument cannot be null. Parameter name: method. I did the research to solve this problem, the solution is changed linking SDK assemblies only. The problem solved, but the app is running, but the app is running slow.

Any one have some ideas to speed up the app.