I am trying to build and deploy a web application. Luckily, I have the option of building the backend in either Python or JavaScript, and would like some help in choosing between Flask or Node/Express.

The application is going to be a website (no framework and a low amount of JS). Users enter some text into a website, and that text is sent to the backend. The backend then does some web scraping with the user-provided text, and computes some result; this result is then returned to the user.

Based on this description, which backend framework would be better for serving many concurrent users? I don't think I'm dealing with "concurrency" per se, since users aren't communicating with each other, but I would like to support many users being able to submit queries at a given time, and each receive a correct answer.

I am also failing to understand exactly why these two choices would be different, except for the choice of language (JS vs Python).

Please note that I am familiar with this site's rules, and am not asking for an opinion of which framework is better - I am asking which framework would be better suited to my use case, and why. My background on this subject is obviously pretty weak, so if you can link to any additional material that might help me understand foundational concepts you think I don't know, feel free to reply with that.

This is my first time trying to build and deploy a website that's more than just a toy application, so apologies if this is a dumb question.