Do you have the opposite experience? A language used by FAANG that doesn’t have performance issues at their scale. They seem to invest a lot in JavaScript which is not what I’d call a performant language and as you’ve said Python.

I’ve used Python for more scripting type tasks and creating basic APIs to get specific jobs done. I’m very weary to go “all in” on Python for an app based on all the feedback about performance.

All that being said I’ve never heard someone say we used X language and it scaled remarkably without issues. I’ve noticed lots of companies eventually go to Java once they get big but nobody really likes to brag about Java apps.

JavaScript (V8 at least) is extremely performant, near native code performance. Considering how dynamic it is, it's not an easy feat but Google, Apple and Mozilla work a lot on it.

Here's a benchmark where JS is 50x faster than Python: https://github.com/kostya/benchmarks

Note that PyPy does much better.