Systems that have a compacting copying garbage collector can, as a side effect, get good locality of data. This is because the compacted heap will be ordered by

Systems that have a compacting copying garbage collector can, as a side effect, get good locality of data. This is because the compacted heap will be ordered by the object graph. This can also potentially happen with promotion to tenured heaps as well, but less directly so. MRI can't do this for various reasons related to its C API though.