Upgrading from Node.js 18 to 20 brought unexpected performance impacts to a Kubernetes-deployed service, as detailed in this technical recap. The experience-driven story reveals how changing memory reservations on Kubernetes pods can shrink Node.js heap spaces—specifically the "new space"—triggering heavier garbage collection and higher CPU load, and how adjusting the --max-semi-space-size parameter restored both speed and stability. https://deezer.io/node-js-20-upgrade-a-journey-through-unexpected-heap-issues-with-kubernetes-27ae3d325646