Rails handled Black Friday and Cyber Monday traffic for an ecommerce company I used to work for just fine. If you are making money, it's worth the cost of 50 lowend VPSes autoscaled (we could have done with a lot less, too).
If we were using Java it would have taken us three times the people and four times as long to build the site, and we all would have been laid off.
> Rails handled Black Friday and Cyber Monday traffic for an ecommerce company I used to work for just fine.
That says nothing about the added cost of running inefficient services, which require additional nodes to serve the same requests and thus increase operational cost and also risk to perform the same service.
If we were using Java it would have taken us three times the people and four times as long to build the site, and we all would have been laid off.