[progn]

> I always assumed cryptography is slower than IO

Cryptography is a CPU-bound operation that often has specialized hardware support. Here's a rule of thumb: in modern computing, IO incurs a greater cost than pretty much anything you can do locally on-CPU. IO is incredibly expensive: cryptography, not so much. If you pipeline your crypto operations and disk fetches, you won't increase response latency at all.

[etfb]

Ruby has a reputation for slowness ([citation needed]?) so is the cryptographic stuff implemented in the language itself or via C-or-equivalent foreign library? I could understand the "too slow, must avoid" kneejerk reaction if it's all in Ruby, even if the reputation is no longer deserved. Human nature.

[FooBarWidget]

Cryptography in Ruby uses OpenSSL wrapper, so it's essentially C.