GILty is a Python app that can use only one core. On a live EKS Auto Mode cluster, sc-karpenter-nodepool picks its instance type by measured single-core performance under the same constraints as the hand-picked r5a.large (at least as many vCPUs, as much memory, at most 10% more money) and finds an r6a.large that runs it about 2.4× faster.
In a terminal: asciinema play demo.cast (or demo-annotated.cast, with the notes as comments). Everything shown was recorded live; long waits are time-lapsed.