Increase touchscreen sensitivity on Nexus 7
In my experience, using your fingers or a stylus does not make any a difference in responsiveness. 

On Skitch, the drawing matches with what you swipe / touch / move, but the responsiveness is slow. Quill is faster (try it, if you still haven't), but it slightly changes what you draw; still faster than Skitch though.

All in all, I think this is probably a hardware issue; could be software too. Nevertheless, we both agree that there is an impedance mismatch!