Not in the vast majority of practical use-cases anyway.

There'll obviously always be the exceptions like Twitter having to migrate off Ruby (Well rails) because scaling is just too hard. But those are exceptions.

And Rails back then was extremely slow. There have always been web frameworks for Ruby with way less overhead.

My direct experience with combating scaling issues in Rails applications always comes back to Rails itself. (ab)uses of Active record, specifically. And sometimes they're very hard to detangle. After well over a decade of doing this sort of work I'm simply not interested in seeing yet another Rails mess.

I do agree that Rails is often a cause of bad performance.

Not in the first place because of its own, or Ruby's poor performance, but because it's easy to write horrible code, and hard to write nice code in it. AR is a very leaky abstraction over a DB. A horrible query always a mere has_many, sort or default scope away. It's MVC horribly unsuited to manage and isolate business logic. The result often indeed being code that performs terrible.