The function of cache memory in a processor is to provide high-speed storage for frequently accessed data and instructions. Cache memory acts as an intermediary between the main memory (RAM) and the CPU, significantly speeding up data retrieval processes. By storing copies of frequently used data closer to the CPU, it reduces latency and improves overall system performance. There are typically multiple levels of cache (L1, L2, L3), with L1 being the fastest but smallest. Efficient use of cache memory is critical for enhancing the processing speed and performance of computer systems.