In a system for providing data and/or computational services, various resources are assigned a sort of points (called vouchers or IOUs) for work manager threads that are currently queued at each resource. When a resource (and its associated resource manager) has a relatively small queue, whereby the resource is holding a relatively small number of points, that resource will be assigned work manager threads for incoming services requests at a high preference, or priority. In this way, faster performing resources can more reliably be supplied with new requests, while relatively slow performing resources will tend not to unduly tie up limited work manager threads in long queues at the slow resources.