[nostrademons]

Idiomatic C++ relies much more heavily on ownership and not so much on refcounting. If you have code that's a rat's nest of shared_ptr, it's going to perform very poorly in a multithreaded environment. But that's why any C++ guru will tell you to not make a rat's nest of shared_ptr. When refcounting is commonly used in C++, like with GUI code or dependency graphs of network requests, it's usually in non-performance-critical sections.

In Python, by contrast, all variables default to object references, and so nearly everything you do involves updating a refcount.

[radarsat1]

Right so you're saying that Python's need to keep ref counts is what leads to the need for synchronizing updates, leading to the need for a lock, more or less. Which is only needed in C++ if you program in a kind of Python style. Makes sense and is a good point.