You're making the assumption that there is a database in the mix for the 100X case. There wasn't, except in-memory. It wasn't a 100X improvement across the board, it was 10X to 100X.
>>sulam+(OP)
Did Twitter ever upgrade past Ruby 1.8? If not these numbers won't be particularly relevant to modern Ruby. (for anyone else reading 1.8 was a simple interpreter and 1.9+ a modern high-performance bytecode VM)