Ruby/Rails is not great for efficiently transforming megabyte sized blocks of JSON into differently structured megabyte sized blocks of JSON, just to give you one example. Golang/Rust/Java is better suited to that. Other use cases are for example any ML-Workloads where Python's ecosystem is much superior to Ruby's.
That being said, you missed my original point, which is that there are problems where you don't really want Rails implemented in a different language because Rails is not a good tool to solve that problem. Think hammer vs saw. You are asking for a different brand of hammer that can cut wood better. Wrong question.
Obviously not every took if right for every job. But your claims that Rails is slow because for what it does there are not many good replacements. Go is a language not a framework.
That being said, you missed my original point, which is that there are problems where you don't really want Rails implemented in a different language because Rails is not a good tool to solve that problem. Think hammer vs saw. You are asking for a different brand of hammer that can cut wood better. Wrong question.