Unity 5: Very high CPU usage on Android related to the GI system

I'm new to Unity, and have just started with Unity 5.

I tested out my very basic scene on Android last night and performance was horrible. GPU usage is fine, but the CPU usage is extremely high, and largely related to GI system according to the profiler. The GI lighting is sucking up ~60% of the CPU usage, and even in a completely blank scene with nothing in it, GI was using 30-40% CPU.

My game has no moving parts, no special shaders, no update scripts.. just a few models (entire scene, grand total of 2100 triangles). Shadows disabled on everything and no colliders.

Testing devices: nexus 7 (2013, lollipop), LG G2 (kitkat). Similar results on both.

Totally empty scene in a brand new project with nothing in it: 80fps
My scene with just a few non-moving, useless gameobjects, 3 materials: 13fps
My scene with only a single diffuse material being reused on all game objects: 36fps
My scene absolutely with nothing but a skybox, 1 light, 1 camera: 50-60fps

Android build properties set at the lowest possible settings has no effect.

This can't be normal...


EDIT: Finally able to grab some screenshots of my profiler. EnlightenRuntimeManager.UpdateEnvironmentLighting seems to be the culprit. This does not even exist when I profile the editor on my PC.

This is with everything as optimized as I've been able to get it. It's currently running about 60fps, but there is hardly anything to it.

On Android:




In Editor (On pc): EnlightenRuntimeManager.UpdateEnvironmentLighting never appears in the list.

 

Well... it seems that was the problem. I was rotating my skybox. I tested a build with the script disabled and the entry using so much CPU usage pretty much disappeared, and framerate jumped quite a bit.

With rotating skybox: 23FPS
Without: 65FPS

I was not aware that rotating the sky would cause the lighting system to have to do so much more work

Thank you very much for the help.

This is my code for the rotation:

Code (CSharp):

1. public float rotationSpeed = 0.85F;
2. float rot = 0;
3. void Update() {
4.         rot += (rotationSpeed * Time.deltaTime) % 360;
5.         RenderSettings.skybox.SetFloat("_Rotation", rot);
6.     }