Hey thanks for the suggestion there for the hands.I'll give that a shot and see how I get on.
I think it's just a combination of two things for me. Firstly I've found that the integrated VR support in 5.2.1 causes a notable drop in performance when compared to me testing the same scene in 5.1.2. Combined with just the nature of the Image hands having a large tri count and the use of multiple cameras being rendered concurrently this is what I think is causing the performance problems for me. Furthermore I did another quick test in 5.2.0 and with no alt cameras available my frame rate is at 65 which shows how erratic it can be.
So the two solutions I have that I could use advice on are:
1) Is there any chance that there are image hands available with just the hand itself - i.e. no forearms? I noticed you have cut rigged hands but if I apply the mesh to your prefabs they just completely deform - I. assuming that they just aren't compatible in that case? A bigger plus to this would be if it's possible to get image hands with a much simpler tri count, on top of just hacking the forearms off (why do they need to be so high at present?).
2) The method I'm using for cameras is to switch between each camera using a depth value. However I can get the performance back up to 80fps if I just use one at a time. Initially I tried to have each camera turn itself off when not in use, but this caused the tracking of the hands to break off from the oculus tracking - perhaps because of the associated scripts? I hoped that by just applying the same depth buffer and image retriever script to every object that had its own camera. Is there a way around this at all? I also put the hand rendering on its own separate camera using depth only and culling everything else in the scene, but even with just two cameras in this instance - the main camera and this depth only one for the hands - the performance took a hit for some reason.
EDIT: In more tests, if I just placed a rigged hand model in the scene, I could get up to 2-3m tris before oculus would start to slow down. However as soon as I start using the leap, that's when performance drops would hit for me. (In this case I was trying out 5.1.3p3 - I'm aware this was below the requirements listed on the downloads page but oculus performance certainly improves when I move down to this version).
[I've also tried the VR planetarium demo and it ran completely smooth for me.]