It does make sense in the web server context to optimize for memory first over compute. This could explain the dynamic you called out. Furthermore, the propensity for many popular gems to have native portions makes the trade off even more useful.

Regarding JIT being faster, types are the next effective tool IMO.

The two drivers I see are:

- JIT has more stack frames to optimize away, allowing more optimization - you addressed this one

- JIT has more information to limit possible outcomes, therefore finding more opportunities