What i drew (with zero lag):

A screencap at 1x zoom:

How much i used of the canvas:

…that was a 20k x 20k canvas.

SAI2 will handle up to 100k. I’m going to go change my underwear, bbs.

…

Also, brush sizes…

EDIT:

Forgot to link the beta page so anyone who didn’t know about it can have a play. In case the fact it’s in Japenese is too confusing:

Those are the links you want.