Performance per watt is a measure of how much useful work a device completes for each unit of energy it consumes. Higher performance per watt means the same task can be done with less power, or more work can be done before a battery dies, a fan ramps up, or a server hits its thermal and electrical limits.
In cyber security, this metric matters because many security tasks run continuously: endpoint protection, log collection, packet inspection, encryption, and anomaly detection. Efficient hardware lets defenders add more monitoring without overheating laptops, draining field devices, or driving up cloud costs. Attackers care too. Malware, botnet agents, and cryptominers are often tuned for low power use so they can persist longer, avoid obvious spikes in heat or battery drain, and stay active on embedded or mobile systems. Good performance per watt can therefore improve both stealth and resilience.