Vuforia Support acknowledged a serious issue with Unity 2019 and iOS A10 processors:
Is there any update on this?
The post says it's related to CPU load and the device tracker. I do not believe this to be the case. In my experiments with an otherwise blank project, I see the lag behavior even when device tracking is disabled. In this scenario (Unity 2019.1, Vuforia 8.3.5), the lag begins as soon as an image target begins to be tracked. I also, don't believe FPS is dropping, the camera feed is just lagging. Xcode logs a bunch of warnings:
Internal: JobTempAlloc has allocations that are more than 4 frames old - this is not allowed and likely a leak
(Filename: ./Runtime/Allocator/ThreadsafeLinearAllocator.cpp Line: 539)
To Debug, enable the define: TLA_DEBUG_STACK_LEAK in ThreadsafeLinearAllocator.cpp. This will output the callstacks of the leaked allocations
(Filename: ./Runtime/Allocator/ThreadsafeLinearAllocator.cpp Line: 541)
This is a serious issue that makes iOS apps built with Unity 2019.1 or 2019.2 un-shipable. I've wasted 2 days diagnosing this issue. Vuforia should be using multiple methods of communication to make it more clear that their product is broken in Unity 2019 so more developers don't waste there time. Why is it not mentioned in the release notes? Why doesn't Vuforia message the users in Unity when they know it's not going to work. How do regressions like this happen? shouldn't Vuforia be regression testing with every new version of Vuforia and Unity?