A method, system, and computer usable program product for improving processor performance during power supply failure are provided in the illustrative embodiments. A throttled condition of a processor is detected in a data processing system. A voltage of the electrical power being provided to the processor is reduced. The processor is un-throttled. Additionally, a frequency of electrical power being provided to the processor may also be reduced. A determination is made whether a condition that caused the throttling has been corrected. In response to the condition having been corrected, the frequency is returned to normal frequency and the voltage is returned to normal voltage. The reducing the frequency operation and reducing the voltage operation may each be performed by distinct components communicating over a data network external to the data processing system.