I'm not complaining about the page or anything, but I'm really surprised how unreliable and fragile are web browsers to pages with javascript. It's using a web worker, but other than that I can't see anything special.
I know you meant unresponsive, but this conjured up a delightful image of your laptop jumping around the room snapping its lid at people like a set of autonomous false teeth.
My graphologies ;)
Sounds like you were lucky.
(See his references section)
If you're interested in this, there was a very good program on PBS's science show Nova a month or two back, called 'the edge of space' or something similar, which involved photography of lightning at altitude and later from the space station, resulting in confirmation that lightning interacts with the upper atmosphere as well as the ground.
