The way I see it, the packages that support both do so because they know over 90% of users are satisfied with the performance of the standard library package and don't want to install extra dependencies to get the library or utility to work.
Even more code just use the standard json package without any fallback. The ease of development or deployment is clearly worth more to them than what small speed advantage they can get from going with the external dependency.
The calculus will be different for Rust, of course, with different build and deployment system.
Even more code just use the standard json package without any fallback. The ease of development or deployment is clearly worth more to them than what small speed advantage they can get from going with the external dependency.
The calculus will be different for Rust, of course, with different build and deployment system.