I don't know, I've been places where select pieces of infrastructure were being rewritten from language X to Y for performance reasons, and it seemed to be goin

I don't know, I've been places where select pieces of infrastructure were being rewritten from language X to Y for performance reasons, and it seemed to be going just fine. It wasn't "we're rewriting everything now" but finding performance bottlenecks and fixing them by rewriting pieces in the new language. It works if you have lots of things communicating over APIs.