[jakobnissen]

The question is why they chose Python for apparently performance sensitive problems in the first place. The fact that they're now bumping against a performance wall and can't get around it by rewriting is a huge drawback when choosing Python as the language in the first place.

Awareness that organisations often end up in these problems should be considered when choosing the language for a green field project.

[draaglom]

The decision likely got made before performance was a major constraint.

As I understand it, Instagram is a python codebase and (guessing) may be the primary motivator here.

Probably the first, say, 100 person-years of effort poured into the Instagram codebase were done at a time when product development velocity, not performance, was the main priority.

[xiphias2]

Instagram wasn't performance sensitive at all. It was iteration sensitive: if the team hadn't done it, some other group of people would have sold a company for billions of dollars to Facebook.