I replied in a few posts in the thread with some details, if you want more there is also this presentation I did at the London performance summit https://www.youtube.com/watch?v=ZSpxuWQK7sM

Most of the performance exploits for the hashtable (which is the driving engine here) are explained after minute 8.30 (although I would suggest you to watch the entire presentstion).

I will present my work at the p99conf as well.