I've noticed that it seems to have at least twice as much lag under Android as it does under Windows. If I draw a wavy line at a comfortable writing speed, the gap between the current location of the stylus and the last pixel drawn seems to be about 2cm under Android, and 1cm under Windows.
Unfortunately, the Hi12 has the same problem as every other general-purpose tablet computer -- the display's framerate is limited to 60fps, and the digitizer's sample rate is limited to about 120hz. As a practical matter, it would be almost impossible to achieve input latencies less than 15ms under those hardware constraints. For comparison, 10ms latency is readily-perceptible, and 20ms latency is enough to make it feel "sluggish" or "sloppy".
Making matters worse, the way Android composes triple-buffered video frames isn't very efficient. Most Android devices (especially those with ultra hi-res displays) are going to struggle to achieve anything faster than 30fps. And even if the OS and hardware can do 60fps, most software is STILL going to drag the effective framerate down to 30fps or less.
Compounding the problem further, you can still draw dozens of pixels in 1/120th of a second with a fast stroke. You could minimize latency by rendering the jagged lines in realtime & smoothing them out a few frames later in a background thread (and in fact, some Android apps make this an option), but most software tries to do the smoothing before rendering anything at all, which takes a bad latency problem and makes it even worse.
As a practical matter, a tablet would need a digitizer sample rate of 500hz or 1000hz, and a display with controller capable of driving it at 120fps (ideally, 240fps) to eliminate most of the perceptible lag & latency (say, 95% of it). To eliminate 100% of it and achieve an effect that's literally visually-indistinguishable from pen on paper, you'd need a 500fps framerate and a 1000hz sampling rate. Motion blur can partially compensate for lower framerates in VIDEO, and increasing the sampling rate allows you to reduce or eliminate time-consuming curve-smoothing, but the only thing that's going to visibly decrease the input lag once you've fully-optimized your software is a higher framerate.
As far as I know, NO currently-available Android/Windows tablet has a 120fps display. Some models of the Wacom Cintiq tablets MIGHT have 120fps displays, but the Cintiq isn't a general-purpose tablet computer... it's literally a dedicated high-end input device whose firmware does NOTHING besides read the digitizer, update the display as quickly as possible, and relay any changes to the host computer running Photoshop.