Earlier quoted context omitted.
You mean heroku because of the excessive cost of over-provisioning their db plans to support traffic spikes with new products?
Yes indeed. Have worked with several clients and chatted with several startups that ultimately decide to migrate off due to extremely high cost as they grow relative to other platforms.
Languages like Python and Ruby are just grossly inefficient. Single-threaded, huge memory profiles, and fully synchronous I/O. Whereas in C#, Tasks and async/await probably provide no shit 10-100x the performance in both compute and concurrency. It would probably be the same deal with Go or Java.
The point is, we tend to hand-wave these kind of choices away on HN. "Just ship it, language doesn't matter". But increasingly, I think it does. You want to make a product with an aggressive free tier, where only like 1% of the user base pays, or some data-heavy analytics thing, these kinds of decisions can be make or break for a business.