When Node.js was first gaining popularity, there were concerns about its single-threaded nature. Single thread means one CPU, and one CPU can be overwhelmed by large traffic influxes. However, for the most part, all of these thread concerns have been assuaged by advances in server technology, hosting, and DevOps tools. With that being said, the single-threaded nature also shouldn't be a deterrent in and of itself: we'll discuss in just a little bit why the Node event loop plays an important role in any discussion around Node.js's performance.
In a nutshell, to really differentiate on performance, we should focus on perceived performance. Python is an easy-to-understand, robust, object-oriented programming language; there are no disputes about that. However, one of the things it does not, cannot, and will not do is run in the browser. That spot is taken by JavaScript.
Why is this important and how does it relate to performance? In a nutshell: Python...
