I doubt there is any significant crunch coming from just encoding/decoding the stream. Most of the time comes still from waiting for network resources, and evaling megabytes of add-in JS. Now the same problem applies to JS, and the counter argument for openness and usability are still the same. Compressed transmission and binary parallel transmission in HTTP/2 are also helping with the comms size.

The project still seems cool, I'll have to have a deeper look into it soon