Comment by amluto

> Why is this thing so slow? It took me five minutes to store a 400 line text file!

> Well, this is just an initial prototype, and don't worry, there's always Moore's law!

Seriously? They're only storing individual bytes in pi:

> In this implementation, to maximise performance, we consider each individual byte of the file separately, and look it up in π.

So the whole transformation should be trivially reducible to a 256-element lookup table from source byte to location in pi and a similar table used to convert back the other way. Maybe a fancy formula could be used for the (never actually encountered) case in which a byte is encoded by one of the infinite available noncanonical encodings.