1. A computer program product for predicting performance of a system comprising a plurality of server tiers, the computer program product comprising: a non-transitory storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising: collecting, for a base allocation of computing resources across multiple server tiers in the plurality of server tiers, a first set of performance information associated with the multiple server tiers for a set of workloads, wherein the collecting comprises applying varying workloads from the set of workloads to the base allocation, wherein the first set of performance information comprises performance information for each of the varying workloads; generating, on a tier-by-tier basis, a set of experimental allocations of the computing resources, wherein each of the set of experimental allocations varies the computing resources allocated by the base allocation for a single server tier of the multiple server tiers; collecting, for each of the set of experimental allocations, a second set of performance information associated with the single server tier for a plurality of workloads; and predicting at least one performance characteristic of one or more candidate allocations of computing resources across the multiple server tiers for a given workload based on the first set of performance information and the second set of performance information.