Can you export to SVG, PDF or some other vector format?
I tested against Adobe Illustrator, Inkscape, iDraw, and Inkpad and was unable to load a file equivalent to drawing for more than about 2 minutes in Sketchology. I'll have a more in depth technical analysis of this soon.
Are you going to be sharing the details of how you've done it or will it remain secret? Just interested because I've done a lot of work with large svgs (sometimes million+ nodes) over the last year (for an ongoing project) so I'm well aware of the performance issues you mentioned.
If you ever decided the secret was too much to bear and you'd like to get it off your chest you could always drop me an email (in my profile) and we could discuss it :)