> And a surprising level of speedup.

Not surprising at all; I keep pointing out that the language benchmarking game is rarely, if at all, reflective of real-world usage.

Any time you point out how slow JS is someone always jumps up with a link to some benchmark showing that it is only 2x slower than Go (or Java, or whatever).

The benchmarks game, especially in GC'ed languages, are not at all indicative of real-world usage of the language. Real world usage (i.e. idiomatic usage) of language $FOO is substantially different from the code written for the benchmarks games.