Why is cache memory smaller than a computer's main memory?

Cache memory is designed to be smaller than a computer's main memory primarily to optimize processing speed and manage costs.

Because cache utilizes static RAM (SRAM), which is significantly faster than the dynamic RAM (DRAM) used for main memory, it is also more expensive and complex to manufacture, as it requires more transistors per bit of storage. By maintaining a smaller capacity, the cache can be integrated directly into or near the central processing unit, reducing the time required to locate and retrieve frequently used data.12

In the memory hierarchy, this smaller size is a strategic trade-off: it allows the system to provide the CPU with near-instant access to the most critical information while relying on the larger, slower main memory to store the bulk of the computer's data.231