There were a variety of experiments with async and I don't think there has yet been any data to show that it improved performance of this benchmark.

[0] https://github.com/TechEmpower/FrameworkBenchmarks/pull/272#... [1] https://github.com/TechEmpower/FrameworkBenchmarks/issues/31... [2] https://github.com/TechEmpower/FrameworkBenchmarks/pull/339#...