Hello All,
This notebook demonstrates fast brushing. On my iMac, it brushes 100,000 points per plot, in twelve plots, for 1.2M points total:
https://observablehq.com/@heman/brush
I wrote my first brushing code in 1988 (tugs white beard 
). At that time, brushing was hot; it was the latest academic research. Building it into a commercial product was one of the high points of my career.
I’ll be really interested to learn whether someone can make this faster!
Thanks for your comments and suggestions,
Heman.