There is a drop in productivity and lags during the following:
-1 follow layer (use macbook cam and web camera)
-2 face tracking FX (use macbook cam and web camera, skype source + screen capture)
-3 iOs demo layer (from iPnone 7s, I suppose that the resolution or dumb data of the video from the phone is much larger and a lot of power is spent for realtime conversion. Perhaps you need a choice of reduced resolution?)
Macbook air, RAM 8, Intel HD 4000, i7, 2GHz
I am sorry to tell you that a MacBook Air (presumable from 2012?) is not capable of running mimoLive smoothly. It seems that the integrated graphics cards don’t perform as others. Especially the face tracking feature needs more GPU power.
However outputting a video frame in different sizes is often effortless for the graphics card because its not scaling the frame for this task it rather looks which pixel from the video frame should it use for this output pixel (so it depends on how many output pixels you have so much the graphics card has to work).
I guess the performance lag for the iOS Demo layer comes from the iPhone 7 video source you mentioned. You may test this by using the iPhone video source in a different layer (e.g. a simple Placer). Unfortunately we can’t ask the iPhone to send less data. This is handled completely by macOS.