The comparison builds Boost.JSON's tree in a monotonic_resource. With its default allocator and precise numbers, boost::json::parse() takes as long as json::parse() on twitter.json, 5% longer on citm_catalog.json and 17% less time on canada.json (M1, C++23 -O3, best of 3 x 30 runs; the arena saves Boost.JSON 28-41%). Signed-off-by: Niels Lohmann <mail@nlohmann.me>