Most people doing serious numeric work don't care about the speed of the Python interpreter because all the heavy lifting is done by optimized libraries like Numpy and TensorFlow.
The fastest dynamic languages I see are those which have no C interface at all. How many of the performance optimizations in a modern JavaScript engine would be possible if it had to support accessing every property of every object as a C string at any point in a program? JS has exactly none of the features that comment claims would be necessary for performance.
This is nonsense. No language ever will have linear algebra or numeric implementations faster than Fortran/C implementations of BLAS, LAPACK etc. Not being able to make ffi calls makes python essentially unusable for most of its niche uses.
> JS has exactly none of the features that comment claims would be necessary for performance.
I don't see people doing ML, scientific computing etc in JS.
I could even use them from TCL if bothered to do so, thus Python's benefits as programming language are meaningless.
Tensorflow has multiple language support for example.
Being the most flexible and user-friendly interface to the most powerful libraries written in other languages isn't meaningless.