I posted this on the Max forum, too:
I'm testing your patch, and I am seeing rates around 8ms when nothing is happening and much longer intervals (~50ms) when I'm actually touching the pad. As you say, that isn't really great for tight control of percussive gestures.
To some extent, you're limited by Max's scheduler. However, maybe you'd have better luck with one of the overlays and a MIDI (or MPE mode)? I expect those should have better timing.