[nathan_long]

> There are (a small percentage of) businesses where speed does matter and caching everything is not an option. Think exchanges, ticket sales, real-time analytics off the top of my head.

True. But even in those cases, there are likely parts of the system where speed of execution is less important than speed of iteration. So you could (if it made sense for you) use a Ruby app for the user-facing app, backed by a service written in something else.

Point being, just because you need a critical processing bit to be written in screaming-fast C doesn't mean you need to write your own HTTP router in C.