I am curious about this being a Unity programmer and and having just myself toured with VDMX for the past several months, esp regarding performance-testing on the new macbook pros.
One thing I would try if i were you: test to see if the unity application itself is lagging itself when you fullscreen VDMX. Try to fullscreen vdmx on an external monitor, and watch the Unity application (hopefully a somewhat basic scene) itself on another monitor. if the unity application appears to lag, remove the syphon server script in unity, rebuild, and test again. I’m curious to see if unity’s ‘run in background’ support is not quite 100%, aside from any Syphon-specific issues.