At a technical level, the biggest problems relate to the way we manipulate frame objects at runtime, including the fact that we expose those frames programmatically for the benefit of debuggers and other tools.
Shoudnt be something that could be tackled with the introduction of a kind of "-g" flag ? Asking the user to make explicit that is willing on having all of this extra information that in normal situations won't be there.
More broadly, the current lack of perceived commercial incentives for large corporations to invest millions in offering a faster default Python runtime, the way they have for the other languages you mentioned in your initial post :)
Agree, at least from my understanding, Google has had a lot of initiatives to improve the JS runtime. But at the same moment, these last years and with the irruption of Asyncio many companies such as Facebook are implementing their systems on top of CPython meaning that they are indirectly inverting on it. -- --pau