OK after watching a few videos of the 3D Jam entries and running my LeapVR on a high powered PC, I have come to the realisation that my Leap is actually a defective unit!
I plugged in another Leap unit and it was a totally different experience.
I wish I had known this before the Jam... it's still a bit choppy on the Mac but not as bad as above.
Is there an on-going place where we can still submit games?