Game got stuck when i use face tracking and face tracking cause phone hot

Hi,all.
when i install and run my app with face tracking on my iphonex,the game sometimes got stuck(everything in game got stuck)，and the game would get right after a little while, this situation would repeat.i also note that if i restart my iphonex,the situation will disappear at beginning, but the sticking would still happen after running the app many times.
when i run app in editor, the remote app installed on my iphonex also got stuck, but in this situation, only the remote app on iphone got stuck, game running in editor is normal, it just can't get face info when sticking. and there is no errors printed in console tab.
In two situations,i didn't find unusual thing in profile.
Another thing, my iphone would become hot when i run app with face tracking, the remote app included in ARKit plugin examples also cause phone hot.
is there anyone know these issues, please help, great thanks!

 

sorry, i checked profile again, and i find gfx.waitforpresent eat 99.5% cpu, and take 7949ms at one frame when my app got stuck

 

Did you fix this? if not try:

turn off vsync? stop using applicaiton.targetframerate if you are? that should remove that.

Make sure your not using ridiculously high poly models or anything, as 7949ms is very very high.