Optimize the functions called in circuit_launch_by_extend_info()
Ref to https://trac.torproject.org/projects/tor/ticket/8902#comment:10
You can see that on a loaded HS, some functions are called quite a lot and they take a lot of CPU.
https://people.torproject.org/~dgoulet/tor-hs-perf-100-circ.png
They should be optimize to bring that CPU usage down.