Fair enough, but parallelism isn't just about cores since SIMD can also help. Also, immutability doesn't just help through parallelism, it also allows other things (as another example, avoiding redundant work like loads of an immutable field and computations on them).
Would that help with a huge 50x difference? Maybe not, but the point is that evaluating the benefits of immutability on a VM that does not optimize it - JS VMs - is not relevant. (And that 50x might also be caused by other limitations of JS VMs and not immutability at all, like say deopts.)
Would that help with a huge 50x difference? Maybe not, but the point is that evaluating the benefits of immutability on a VM that does not optimize it - JS VMs - is not relevant. (And that 50x might also be caused by other limitations of JS VMs and not immutability at all, like say deopts.)