We have a service that can generate million of transactions in short period of time, even few seconds. We started the API backend with RoR on a robust cloud service. We had few customers at the beginning and few transactions. Then, before starting the first big event we made some load test, and we understood that we needed more performance. We have changed the platform many times: servers, languages from RoR, C++, C#, C# mono, to Go. Now, we are still using Go. I will show you the pros and cons in all different scenarios.