Some parts of the process are obviously not ones where it makes sense to squeeze out every CPU cycle. Sometimes programmer time (both in development and maintenance) is your scarce resource (either because of total numbers, or people with specific knowledge), and so it is far better to optimize for that.
In most cases (Python, Ruby, etc...) is it even possible to find your hot-loops and replace them with C/C++/Rust/etc... code. So you can really focus on those small areas where that would make an actual difference.
Additionally, in some places where you need concurrency you can split up the task into parts that have little to do with each other, and there Python is a great glue language to manage calling other executable that do the actual work.
In most cases (Python, Ruby, etc...) is it even possible to find your hot-loops and replace them with C/C++/Rust/etc... code. So you can really focus on those small areas where that would make an actual difference.
Additionally, in some places where you need concurrency you can split up the task into parts that have little to do with each other, and there Python is a great glue language to manage calling other executable that do the actual work.