what's the conditions by main loop checked befor enter a frame works?

$$anonymous$$ guys, we are make a project about some works like movie play, camera preview and so on with Unity3d on Android platform, but we have some problem about unity's main loop. it will drop a frame regular. t$$anonymous$$s is sad. some context can make it happend:

1. play 4k/60fps/60bps movies.

2. play a movie, i request a FBO with 4096*4096 size .

3. play a movie and camera preview in one scene Simultaneously.

PS: movie is a native file,i use Android's SurfaceTexture,Surface,OpenGLES FBO... render to texture to Unity Texture2D, Camera Preview is like t$$anonymous$$s too.

i have a systrace like t$$anonymous$$s ,the red flag is where Unity drop a frame work: