There are no HFT exchanges in the bitcoin world. All these trades are done over the internet using HTTP. Hardly HFT.
HFT is when you are faster than most other traders. ;)
Liked how you pattern match directly on JSON messages, I should di it more. :)
There are institutional-grade solutions (cross-connect, colocation in NY4, FIX feeds / order placement), available e.g. from Gemini (https://gemini.com), however, I am not sure that current overall Bitcoin trading volume is enough to warrant this. Both one-time setup and monthly fees for direct links are significant.