I was hesitant as to how much I should go into this because you get into the semantics of the benchmark but this [0] thread goes into why - that particular implementation doesn't behave the same way as the other implementations, it uses a different db driver that doesn't synchronise, which won't be allowed in the next version of the benchmarks. Techempower publish regular snapshots of their benchmarks at [1], and if you look at any of the snapshots that aren't the last published set where the discrepancy was fixed you'll see that all of the js implementations lag far far behind.
[0] https://github.com/TechEmpower/FrameworkBenchmarks/issues/72...