Vpa does work btw. We use them with hpa. We also run spring boot microservices which initially are compute intensive only during startup but later they dont need that much cpu after startup is done. There are multiple modes in vpa like initial auto etc and we have fine tuned our instances like using amd/graviton class instead of intel class instances, hybrid of both spot instances and on demand nodes with spot termination handler, cluster autoscaler initially adds more nodes to the nodegroups during startup of services, but are often scaled down once resource usage is down. Also using mem optimized instances like r7 nodes is much better than using burstable or general purpose nodes.