Julia's multimethods approach can handle type information when available. You can have the interface--and corresponding performance profile--that you prefer. Not only is it faster, the speed is much more knowable because you don't rely upon the runtime engine and/or emcc to figure out where it can optimize because the type, despite not being stated, is actually fixed and can be made fast.

Julia is roughly twice as fast as JS (Node) on the Computer Languages Benchmark Game benchmarks: https://benchmarksgame-team.pages.debian.net/benchmarksgame/box-plot-summary-charts.html

Julia also has better syntax for interacting with data.