Using Eden Treaty requires a lot of down-level iteration to map all possible types in a single go, while in contrast, Eden Fetch can be lazily executed until you pick a route.
With complex types and lot of server routes, using Eden Treaty on a low-end development device can lead to slow type inference and auto-completion.
But as Teasim has tweak and optimized a lot of types and inference, Eden Treaty can be perform very well in the considerable amount of routes.
If your single process contains more than 500 routes, and you need to consume all of the routes in a single frontend codebase, then you might want to use Eden Fetch as it has a significant better TypeScript performance than Eden Treaty.