VMware recently released a white paper on the power and performance improvements in the Host Power Management (HPM) feature in vSphere 5.5. With new improvements in HPM, one can save significant power and gain decent performance in many common scenarios. The paper shows that power savings of up to 20% can be achieved in vSphere5.5 by using industry standard SPEC benchmarks. The paper also describes some of the best practices to follow when using HPM.

One experiment indicates that you can get around a 10% increase in performance in vSphere5.5 when deep C-states (greater than C1/halt, e.g., C3 and C6) are enabled along with turbo mode.

For more interesting results and data, please read the full paper

Note: HPM works at a single host level as opposed to DPM which works on a cluster of hosts