Systems, methods and computer program products assess processor performance metrics by monitoring probes constructed using instruction sequences. A first probe value can be determined from execution of a broad spectrum probe in an execution environment. In response to determining that the first probe value is not a first expected probe value, a targeted probe providing a second probe value directed to a subsystem of the execution environment, a feature of the subsystem, or a component of the execution environment is executed. In response to determining that the second probe value is not a second expected probe value, a differential between the second probe value and the second expected probe value can be used to determine that a bottleneck exists in at least one of the subsystem of the execution environment, the feature of the subsystem, or the component of the execution environment.