Efficiency-Cores are specialized processing units designed to handle less demanding tasks while consuming less power. They are part of a larger architecture that includes more powerful cores, allowing devices to balance performance and energy efficiency. This design is particularly useful in mobile devices and laptops, where battery life is crucial. By offloading simple tasks to Efficiency-Cores, systems can maintain high performance for more intensive applications without draining the battery quickly. This approach helps improve overall system responsiveness and extends the time between charges, making it ideal for users who need reliable performance on the go.