Benchmarks are often not a great indicator for real world performance, especially for Javascript. Benchmarks are very constrained, repetitive and often numeric

Benchmarks are often not a great indicator for real world performance, especially for Javascript. Benchmarks are very constrained, repetitive and often numerical code that is executed a lot of times with similar input. This gives the JIT a lot of opportunity to optimise and specialise for specific types. These tools are usually not long-running , so code has to be JITed all over again on each invocation. A lot of code will probably only be executed a few times, so might only be executed by the interpreter or low tier JIT. There will also be a lot of AST construction, walking and modification, which is really difficult to optimise without the guidance of types. A lower level language can use better data structures that don't require so much pointer chasing. Also lots of potential GC pressure if there are multiple internal representations to construct. JS can be insanely fast for what it is, but alot of the weaknesses are apparent with short-running tooling. There is also a reason why most complex,JS heavy web apps seem to get laggy and slow eventually...