[vvanders]

> simple values

So does every other language, where it matters is with objects. Until I can mark a whole object as a value type and fix it in memory relative to other objects then you'll pay a 10-50x slowdown for cache misses and the like.

[Klathmon]

Sorry, that should have said "simple objects".

But you don't even need to rely on that. JS has TypedArrays[0] which are basically just a chunk of memory you can read and write to.

Aside from some bounds checking, it's about as "low level" as you can get. Sounds like exactly what you are looking for.

[0] https://developer.mozilla.org/en-US/docs/Web/JavaScript/Type...

[vvanders]

Typed arrays are close, but still not good enough.

On the Java side I've used ProtoBuf for similar approach(using byte[] which does have memory placement semantics). While it helps, the bounds checking and accessors that you need still have a non-trivial cost both in branching and cache thrashing(len is usually stored for an array at a different location or at the head so data items near the mid/tail will still take a hit).

Realistically you can get within about 1/5th the speed of native using cache aware data structures and techniques. As always it matters if your use case needs that speed but choosing a JS/managed based tech-stack will always limit you from getting that last 5x perf improvement.