I think people overestimate how much CPU time a typical CRUD app spends on actual business logic, even with an interpreted language like Ruby or Python. What I’ve seen is the bottleneck is largely memory, such that you can pack a ton of these apps on a machine with a few cores and a lot of RAM.

The stuff that actually is CPU-bound often ends up being written in an appropriate language, or uses C extensions (e.g. ML and data science libraries for Python).