I've had a problem since late 2018 with bad FPS in landscape mode on my devices (Honor 8 and Honor 9). Currently Unity 2019.2.0f1 and Vuforia 8.3.8
If I set the Orientetion to Portrait in Project Settings/Player/Resolution and Presentation it works perfectly. But if I put it to Auto Rotation and flip it to landscape it starts ok but degrades over time, finally its just stuttering at about 5-8fps.
I tested both to change it to Portrait only/Auto rotation in Project Settings/Player/Resolution and Presentation and changing it by script (I want to have portrait only in main menu and auto rotation in AR mode)
if (sceneName == "Main Menu")
Screen.orientation = ScreenOrientation.Portrait;
else if (sceneName == "AR Scene")
Screen.orientation = ScreenOrientation.AutoRotation;
I have a UI on the Camera with a lot of different elements on it, maybe it could be something there that's causing the problem?