1.4 - Computer Performance

The faster a CPU can process data and instructions, the faster programs will run, tasks will be completed quicker, and the overall running of the computer will be smoother.

Three key factors affect the performance of the computer and especially the performance of the CPU:​ 


Cache Memory

As to be explained in Primary Storage next, cache memory is a type of storage that can be accessed by the CPU extremely quickly (because it is so close to, or even within, the CPU).

Cache memory is used to store data that is frequently accessed. It can be accessed faster than other types of memory, such as RAM.  Therefore the more cache memory in a computer system, generally the better the performance will be.

However, cache memory is very expensive, so most computers only have a small amount. 


Clock Speed

The CPU speed is called the clock speed. The faster the clock speed, the faster the computer can perform the FDE cycle resulting in better performance because more instructions can be processed each second.

Clock speed is measured in gigahertz (GHz) and a good desktop clock speed for the early 2020s is around 3.5 GHz. A gigahertz is equal to a billion hertz (cycles) that can be performed in a second.

The clock speed can be altered to affect performance

  • Overclocking is a technique that increases the clock speed above its factory setting, which will improve the performance but risks damaging the computer and shortening the system's lifespan.

  • Underclocking will lower the default clock speed to decrease performance but maximise the lifespan of the system.


Number of Cores

A core is a term that describes the processing components within the CPU (control unit, ALU, registers and internal memory). A single-core CPU will contain one set of processing components whereas a multi-core CPU will include more than one set (such as dual (2) or quad (4) processors).

The more cores a CPU contains, the more instructions can theoretically be fetched, decoded and executed at the same time.

However, the number of cores a CPU has doesn't necessarily mean the performance will be better as older software is not written for multi-core computers and cores may have to wait for other cores to finish processing. 

Questo's Corner

Cache Memory:

a. What is cache memory?

b. Explain why more cache memory generally means better performance.

Clock Speed:

a. What is clock speed measured in? What is the average modern clock speed?

b. What is meant by overclocking and underclocking?

c. Explain why a higher clock speed generally means better performance.

Number of Cores:

a. What is a multi-core processor?

b. Explain why a CPU with more cores usually means better performance. 

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