In terms of performance, CSS Modules is a really great balancing of concerns. Of course you get all the benefits of locally-scoped CSS, but when compiled for the browser, CSS Modules performs exactly the same as regular CSS since there's literally no runtime. It just generates a static CSS file, and your markup then references it like you normally would.
For my needs, I find this particularly useful in a large organisation where we need to settle on a common way of building UI components that can be shared between teams. Being able to generate components with co-located styles without incurring a performance or bundle size cost makes it a much safer bet across an entire company.