Heck, we saw crazy performance degradation with redis when its memory usage exceeded a single NUMA block. Not much to be done about that at the k8s level when redis is single-threaded. Have to be super conscious of the underlying hardware at that point.
In that case I run one redis instance per NUMA domain. On my home server I essentially split machine in two and treat it as two distinct machines. PCIe devices attached to a proper domain etc.