1. A method comprising: by a cloud services system, determining a baseline actual hardware performance utilization of a plurality of hardware computing devices for a plurality of applications in accordance with an initial mapping that maps a plurality of hardware resource classes to the plurality of applications, wherein each of the hardware computing devices is associated with one of the plurality of hardware resource classes; by the cloud services system, determining a lower-cost configuration in which each application is assigned to the hardware class having a lowest equivalent cost for that application; and by the cloud services system, when the sum of the lowest equivalent costs for each application assigned to a particular hardware class by the lower-cost configuration is less than a threshold value, moving one or more applications from their initially-assigned hardware classes in the initial mapping to the particular hardware class.