I'm in the middle of putting together a Unity game and have been tinkering with a Gear VR build (it's otherwise been android focused so far). Unfortunately I've been seeing spikes in the Unity profiler unique to the GearVR build that are causing unacceptable juddering in game:
I originally wondered if I was trying to push too hard graphically so for the purpose of testing the problem I stripped out any non essentials. The screengrabs are taken using a minimal build which appears to be well within the draw call / poly limits that often come up in GearVR optimisation articles (at the point of the screenshots 13 SetPass Calls, 23 Draw Calls, Tris 31k, Verts 57k.)
Some details if it helps then: I'm running Unity 5.4.2f2, testing on a Samsung S6. Geometry is procedural but batched after instantiating. Shader is Digicrafts Colorbox (Unlit Gradient) however problem persists using Vertex Lit or Mobile Diffuse. Skybox is also Colorbox, again changing this to an alternative or to solid colour has no impact. Quality is fastest but with 2xMSAA (same result if set off). No other lighting, shadows etc in scene. Canvas is turned off for the purpose of testing. Forward Rendering Path. Camera clears to Skybox (no improvement changing to soid colour). The issue does not appear on the standard (non VR) android build nor in the editor.
I know there is no magic answer here since you can only go by what I've written and the screenshots but could someone please point me in the right direction for the RenderForwardOpaque.Render / Clear issue ? I'm presuming VR:WaitForGPU is related to this but I don't otherwise know what it is or what I can do (if anything) to alleviate the issue. Where should I be looking to solve this ?