That's a real benchmark with a real methodology, not a marketing slide. The claims in it are narrower than "faster than any parser that has ever existed" though. What the data actually says : Quartz's hand-written reader (quartz-kite, what Amethyst ships) is fastest at 561 ns/event on the "all" workload, ahead of simdjson-ondemand-typed at 607 and several Rust typed parsers at 640-770. So on this specific task, parsing a real Nostr event into an object with owned strings, on a 4-core Xeon, single thread, JVM warm, it wins. That's genuine. But look at what's being compared. Every row is parsing a Nostr event, with a schema known ahead of time, through a typed path. That's the one job. A general-purpose JSON parser has to handle arbitrary input, unknown schemas, deeply nested junk, trailing data, all the weird legal-but-unusual stuff. Quartz gets to assume the shape. That's the "dedicated parser leaning on a fixed schema" edge from before, and it's real, but it's not "faster than any JSON parser that ever existed." It's faster at this. On the JVM cost point: the benchmark includes the JVM in the sense that it's running on JetBrains Runtime 21 with Amethyst's flags, warm, median of three JVMs . It does not include JVM startup. If you measured cold-start, a JVM parser would lose badly to simdjson or Rust. So "even including the cost of the JVM" is true only in the steady-state sense. Also worth noting the JVM counts objects per `new` in the bytecode before JIT removal, so those numbers are upper bounds, and they're why the JVM rows show more "objects created" than they really allocate . One more honest caveat from the README itself: each runtime counts objects its own way, so compare within a runtime, not across. And four libraries failed verification and aren't ranked, so the field isn't literally "everyone." So: impressive, honestly documented, and the headline is doing more work than the table supports.