The first myth is "Python is not slow" - it is debunked, it is slow.
The second myth is ""it's just a glue language / you just need to rewrite the hot parts in C/C++" - it is debunked, just rewriting stuff in C/Rust does not help.
The third myth is " Python is slow because it is interpreted" - it is debunked, it is not slow only because it is interpreted.
This is strange. Most people in programming community know python is slow. If it has any reputation, it's that it is quite slow
Except it does. The key is to figure out which part you actually need to go fast, and write it in C. If most of your use case is dominated by network latency.
Overall, people seem to miss the point of Python. The best way to develop software is "make it work, make it good, make it fast" - the first part gets you to an end to end prototype that gives you a testable environment, the second part establishes the robustness and consistency, and the third part lets you focus on optimizing the performance with a robust framework that lets you ensure that your changes are not breaking anything.
Pythons focus is on the first part. The idea is that you spend less time making it work. Once you have it working, then its much easier to do the second part (adding tests, type checking, whatever else), and then the third part. Now with LLMs, its actually pretty straightforward to take a python file and translate it to .c/.h files, especially with agents that do additional "thinking" loops.
However, even given all of that, in practice you often don't need to move away from Python. For example, I have a project that datamines Strava Heatmaps (i.e I download png tiles for entire US). The amount of time that it took me to write it in Python in addition to running it (which takes about a day) is much shorter than it would have taken me to write it in C++/Rust and then run it with speedup in processing.
Like, I wouldn't say it's a "myth" that Linux is easy to use.
For that matter, I recently saw a talk in the Python world that was about convincing people to let their computer do more work locally in general, because computers really are just that fast now.