So, it would be interesting to see how much lag different tablet models generate, or even the variation for users with the same tablet model.
How to measure:
I counted to 13 frames @ 60 fps = 1/60 x 13 = 217 ms
My setup:
P3P, fw:1.3.20
Tablet: Nexus 7 II, android 5.1.1
How to measure:
- I suggest to set the video mode to NTSC to get the 60 fps capability, and then set the video format to 720p, 60fps (tap "Fn" above the record button to set this)
- Place the tablet in front of the copter/camera so that you can see the tablet in the video (does not matter if out of focus and blurry)
- Start recording and just move some object in front of the camera a couple of times
- Open the recorded video in some video editing software and count the number of frames of the delay/lag
I.e. the number of frames it takes for the object to appear at the same spot in the first generation, compared to the second generation.

I counted to 13 frames @ 60 fps = 1/60 x 13 = 217 ms
My setup:
P3P, fw:1.3.20
Tablet: Nexus 7 II, android 5.1.1