Skip main navigation

The speed & perception of computer systems

If computers are always getting faster, why does yours seem so slow? This article discusses a few potential reasons that this happens.

Over time, CPUs have grown faster and more powerful. You might therefore expect that computers would always be faster nowadays than in the past — and they often are.

Speed and perception

In a like-for-like task, like adding together a trillion numbers, a modern-day computer would have a clear advantage over a 20-year-old machine because of its more powerful CPU. However, at the same time, the amount of work people expect computers to do has also increased dramatically.

Nowadays, computers must:

  • Render life-like films and TV shows
  • Provide interactive communication, with the user experience in mind — animations and updates
  • Process thousands of financial transactions in an instant
  • Protect their data with antivirus software
  • Run increasingly complex operating systems and other software
  • Interact with more advanced peripherals

We will now examine how some of the tasks above might impact modern computer systems.

Data integrity and security

Until the 1970s, hardly any computing power was spent on checking the accuracy or security of data. Today, however, whenever data is sent from one computer to another, they communicate using a variety of protocols, each requiring additional information to be sent. One of these, called Transport Layer Security (TLS), ensures correct and secure data transmission. However, protocols like TLS require modern computers to have more memory and processing power compared to a computer in the 1970s.

Software

The complexity of operating systems, games, applications and many other pieces of software has also increased.

Imagine that you are playing a modern video game. Each time you press a button, the operating system needs to perform between 10 and 20 steps before you see the output. This delay, between when a user interacts with a computer (the input) and when something happens (the output), is known as latency, and is measured in milliseconds (ms).

An illustration of latency

Increases in data usage and transmission

You may want to transfer some money to another bank account. Twenty years ago, you had to go to the bank, wait in a queue, and ask the cashier to set up the transfer — which could then take a week to process. Somewhere along the line, computers would be involved, but there was not too much work for them to do. Today, you can do the whole thing from a mobile device, with funds transferred instantly. That’s great for the user, but involves a lot of extra data processing: setting up secure connections, sending information about the transaction itself, and additional data for the many protocols. The computers involved execute significantly more instructions than their predecessors did. The same is true for many other common tasks.

Screen resolution

What about the computer monitor or screen on which you are looking at your bank transactions? Could changes in monitors affect computer speed? A monitor consists of a square grid of pixels, each comprising three lights (red, green, and blue). By changing the intensity of each light, the computer changes the perceived colour of the pixel.

However, monitors have also advanced considerably. To meet users’ higher expectations of the display quality, modern monitors have a much higher resolution, meaning that the same size of the screen has far more pixels — there are often hundreds of thousands or even millions of them. The computer must calculate and set the desired colour for all those pixels, so a larger resolution requires more computing power.

This article is from the free online

Understanding Computer Systems

Created by
FutureLearn - Learning For Life

Our purpose is to transform access to education.

We offer a diverse selection of courses from leading universities and cultural institutions from around the world. These are delivered one step at a time, and are accessible on mobile, tablet and desktop, so you can fit learning around your life.

We believe learning should be an enjoyable, social experience, so our courses offer the opportunity to discuss what you’re learning with others as you go, helping you make fresh discoveries and form new ideas.
You can unlock new opportunities with unlimited access to hundreds of online short courses for a year by subscribing to our Unlimited package. Build your knowledge with top universities and organisations.

Learn more about how FutureLearn is transforming access to education