How Cache, Clock Speed and Cores Affect Performance
Learn how cache size, clock speed and number of cores affect CPU performance, when each helps, and why no single specification guarantees a faster computer.
A larger cache, faster clock speed and more cores can each improve CPU performance, but they help in different ways. None guarantees that every program will run faster.
Cache size
The cache is a small, fast store of data and instructions that the CPU is likely to need soon. If the CPU finds what it needs in the cache, it can usually access it faster than if it has to fetch it from main memory (RAM). A larger cache can hold more useful data, reducing time spent waiting for RAM. Its benefit depends on what the program needs and whether that data is actually in the cache.
Clock speed
Clock speed tells you how many cycles the CPU clock makes each second. A higher clock speed means the CPU can carry out more cycles in the same time, which can help it process instructions faster. But a cycle is not necessarily one completed instruction. Clock speed alone cannot tell you which of two different CPUs will perform better.
Number of cores
A core is a part of the CPU that can process instructions. More cores allow more work to be processed at the same time, such as running separate tasks or dividing a suitable program into parts. This helps most when there is work that can run in parallel. If a task must be done one step after another, adding cores may make little difference to that task.
For example, a computer running several programs might benefit from extra cores, while a program repeatedly using the same data might benefit from a larger cache. Exam mistake to avoid: do not say that doubling the cores doubles the speed of every program. Always link the performance gain to the kind of work the CPU is doing.
