Due to the inherent constraint of JSON, the exact use case would matter a lot for such comparisons. Simdjson is generally faster when you only want a well-formedness check or a very small proportion of a large input JSON, but the "well-formedness" for JSON would be a small subset of the "well-formedness" of binary formats, and a partial parsing performance is often dominated by language bindings instead of underlying parsers (it is a wise move that simdjson also has a JSON pointer support for this reason, because that greatly reduces FFI overhead). Binary formats in comparsion tend to have a generally flat performance profile.