Ask HN: What companies changed from Python to another language?

Twitter switched some of its code from Ruby to Scala. I do not know the exact scale of the matter, but companies do change their stack as things get more complex.

I've read articles from Dropbox's engineering blog about their move to go for performance critical parts.

The question is, how many companies (and who are they) who have switched from Python to a different language/platform and stuck to it? Most importantly, why? GIL? Distribution? Other?