1. A method of operating a resource management node comprising: identifying an unproductive group of guest virtual machines (VMs) that satisfy a defined rule for being unproductive on a first group of physical host machines based on infrastructure of a distributed computing system used by the first group of the physical host machines to host the guest VMs, wherein the identifying comprises: for each of a plurality of the guest VMs determining a productivity metric for the guest VM based on infrastructure resources of the distributed computing system that are used by execution of the guest VM on the physical host machine, and controlling a time window over which the productive metric is measured based on an elapsed time needed for the physical host machine to transition from start-up to being ready to execute the guest VM and based on observed change in number of VM guests being executed by the physical host machines over a defined time, including increasing the time window over which the productivity metric is measured responsive to a slower start-up indicated by a longer elapsed time and shortening the time window over which the productivity metric is measured responsive to an increase in the number of VM guests being executed by the physical host machines over the defined time; and adding to the unproductive group any of the guest VMs having a productivity metric that does not satisfy a defined utilization rule; generating a relocation scenario for relocating the unproductive group of the guest VMs from the first group of the physical host machines to a second group of the physical host machines to change utilization of the first group of the physical host machines and change utilization of the second group of the physical host machines; estimating an effect of the relocation scenario on how much infrastructure of the distributed computing system would be used by the first group of the physical host machines and the second group of the physical host machines if the relocation scenario is performed to relocate the unproductive group of the guest VMs from the first group of the physical host machines to the second group of the physical host machines; and responsive to the estimate of the effect of the relocation scenario on how much infrastructure of the distributed computing system would be used satisfying a defined rule, relocating the unproductive group of the guest VMs from the first group of the physical host machines to the second group of the physical host machines by performing the relocation scenario.