How to choose an option for handling speech sounds between Python and JavaScript?

Question

speech synthesis

1. Is there a big difference between Python and JavaScript when processing speech sounds?
As far as I know, Python is the best option for data processing, because according to the source , Python's computational speed and performance are much higher than JavaScript. According to programmers who write in JS, they use a JS-based framework, despite the difference in speed. In the near future, the speed of JS will increase to the level of Python.

2. Tell me, what is the best framework for processing speech sounds and displaying them on a graph?
I'm only familiar with D3.js . But there is a small problem of how to choose the right framework. because currently there are different libraries\frameworks like ml5.js(rather young, but very promising) and p5.js .