Rails has a tendency to turn an I/O-bound problem into a CPU-bound one. with those hundreds or even thousands of object allocations per request, and dozens of a

Rails has a tendency to turn an I/O-bound problem into a CPU-bound one. with those hundreds or even thousands of object allocations per request, and dozens of abstraction layers, no amount of async magic powder is going to save you. At the same time, fiber-based concurrency does look promising for lighter weight Ruby web stacks.