Device.Present profiling

I’m having a hard time understanding why my iphone game is running so poorly. I basically just have a few particles that are rendered in camera 2 to a rendertexture. Then that gets used by the maincamera on some geometry. I’m too unfamiliar with unity iphone to know if I’m running into a bug or just overtaxing the iphone gpu with this very simple scene.

But especially i’m confused by the behavior of Device.Present. It oscillates wildly even though the scene isn’t changing. Is this some kind of strange VSync behavior? Is it just the CPU waiting on the GPU? And if so, why would the GPU be oscillating?

If anyone can help me understand what Device.Present is and how to more effectively profile on my iphone, it would be much appreciated. Thanks!

Oh - and here’s a screenshot of my profiler:


Someone from Unity answers this question for god’s sake. It’s been 6 years since it was first posted.