iOS Camera.Render spikes in profiler

hi, I’m making a VR app and encounters inconsistent performance spikes.
Screenshots are profiler images from a builded iOS app.
[60750-스크린샷-2015-12-28-162402.png|60750]

[60751-스크린샷-2015-12-28-162725.png|60751]

as you can see, the Camera.Render occasionally spikes up to ~25fps, but the profiler doesn’t tell exactly what causes it.

Does anyone can explain what this is, or recommend what to do??

Did you find a solution for this problem?