Dropbox has had several headaches from its reliance on python, first among all from the fact that Python is still bound on running once thread at once on a single core after all these years (thanks GIL), so it does not parallelize at all without abusing subprocess + IPC.

That's the reason why they attempted writing a new runtime first (Pyston), and then settled down on rewriting their performance critical infrastructure in Go (https://blogs.dropbox.com/tech/2014/07/open-sourcing-our-go-...)

Google iself wrote grumpy for the same reason, which is that CPython scales pretty bad.

No I get that. And they employ the creator of the language just that it was doable but not necessarily enjoyable.

doable sure. But enjoyable? ;-)