I know the argument, I don't buy into the argument (actually not a rubyist). Ruby just imposes some factor x on the performance as compared to Java roughly spea

I know the argument, I don't buy into the argument (actually not a rubyist). Ruby just imposes some factor x on the performance as compared to Java roughly speaking. Which means you'll start a little earlier to look into queuing requests, distributing stuff in ruby as opposed to a java or go application. Nevertheless if we talk about scale, this is just a constant multiplier. With a kafka queue, and worker nodes, compute-heavy jobs are easily distributed across many worker nodes. For many parallel requests, you load-balance. If the PostgreSQL or mysql table is the bottleneck (persistence layer), well this is actually a design decision thats orthogonal to the programming language (PostgreSQL won't scale better with a JDBC ORM).