Shopify invest heavily in Ruby and write plenty of stuff in lower level languages where they need to squeeze out that performance. They were heavily involved in Ruby's new JIT architecture and invested in building their own tooling to try and make Ruby act more like a static language (Sorbet, Bootsnap).
Runtime performance is just one part of a complex equation in a tech stack. It's actually a safe bet that their Ruby stack is pretty fucking solid because they've invested in that, and hiring ruby and JS engineers is still 1000x easier than hiring a C++ or Rust expert to do basic CRUD APIs.
Runtime performance is just one part of a complex equation in a tech stack. It's actually a safe bet that their Ruby stack is pretty fucking solid because they've invested in that, and hiring ruby and JS engineers is still 1000x easier than hiring a C++ or Rust expert to do basic CRUD APIs.