A lot of handwaving about hAx in the benchmarks but many of these claims are from people who got their information secondhand (or worse). Actually reading code from the top submissions in the techempower/FrameworkBenchmarks repo (organized neatly under the frameworks/ directory hive) yielded valuable insigthts for me:
* Pipelining SQL requests has a massive effect on RPS for web services that will access SQL databases
* A well-maintained HTTP2/HTTP3 web server written in c named h2o is relevant in 2026, even if it is used as a proxy that delegates business logic to simpler web service workers written in Rails or in python 3 (via Gunicorn)
* For web services that write to a SQL database, the Axum rust stack, now with a healthy ecosystem of middleware modules, may provide up to twice the RPS as the Spring (Java) stack (externally discovered: at lower CPU and much lower RAM usage)
* Even frameworks written in JS (hyperexpress, just-js) or python (aiohttp) can vault into the realm of top-10 performers if they leverage OS-level asynchronous IO and SQL pipelining.