7 Reasons Why Your Computer is Slow

You're probably reading this because your computer is slower than it used to be.

Computers slow down with age. Here are some of the reasons why and what you can do to fix them.

1. It’s running out of RAM

You probably know that your computer has two types of memory:

  • RAM chips - which are only used when it’s turned on. 
  • Data storage - hard disk drive (HDD) or solid-state drive (SSD).

Generally, a computer runs faster when it has more RAM, because this is what’s used for processing the apps you run.

How to fix:

  • Short term - reboot your computer, as this clears the RAM.
  • Longer term - add more RAM.

2. The processor is out of date

Ultimately, your computer’s performance is capped by its processor. Every computer has one and generally, the older they are, the slower they are. 

Even new computers have different processors. High performance devices, such as those designed for serious gamers and people doing intensive graphic or video work, will have more advanced (and therefore more expensive) processors.

How to fix:

  • It’s difficult to replace a processor. If that’s your problem, it’s probably time to replace your computer. 

Read our guide to buying a used laptop.

3. The hard disk drive is almost full

Your hard disk drive is where all your files and apps are stored. It’s also space that your computer uses while you’re using it. Which means that if the disk is low on space, your computer will run more slowly.

Once the drive reaches around 80% capacity, you should assume it’s low on space. Having 20% (one fifth) of the disk spare may seem like quite a lot, but it’s not. 

Part of the problem is that your data is stored in fragmented blocks across the disk that’s inside the drive. That 20% is made up of small gaps, scattered across the disk. Your computer has to work hard to find and use those spaces.

How to fix:

  • Defragment your disk - this makes those spaces larger.
  • Delete unused data - old apps and files you don’t need.
  • Back up data - find somewhere else to store data, such as old photos.
  • Upgrade your disk - install a larger one, although you’ll need to transfer all the data from the old one.

4. Too many apps are launching at startup

Many apps like to make themselves convenient to use by launching when the computer is turned on. That way, they’re fast to fire up when you need them. Unfortunately, each of these apps uses some of your processing power and can cause your computer to run more slowly.

How to fix:

  • In Windows 10, go to Task Manager and turn off specific apps.
  • To stop these apps running in future, go to Startup Apps and turn them off.
  • On a Mac, go to System Preferences to remove apps set to start on login.

5. It’s infected with malware or a virus

If your computer has suddenly begun to slow down, it could be that malware (malicious software) or a virus is active. 

There are many forms of malware and they can be picked up from all kinds of places, including:

  • Visiting a compromised website
  • Downloading an app
  • Plugging in someone else's USB stick

How to fix:

  • Run a virus or malware checker, although this isn’t guaranteed to fix the problem. One free version to consider is Malwarebytes.
  • Have your computer checked over by an experienced professional.

6. The operating system has become cluttered with junk

Many people who work with computers will completely reinstall their operating system, such as Windows 10, every year or so. They do it because it improves the performance of their computer.

Over time, operating systems become cluttered with all sorts of bits and pieces of data. These are picked up as apps are installed, used, upgraded and deleted. As the operating system becomes increasingly untidy, it slows the whole computer down.

How to fix:

7. Your computer is overheating

Everything your computer does generates heat. If the processor gets too hot, it slows down, or can even be permanently damaged.

To keep your computer cool, it’s equipped with a fan, which usually runs faster as the computer warms up. If the fan vents are blocked by anything, the heat will build up. Blockages can be caused by positioning something against the vents or by the natural build-up of dust.

How to fix:

  • Keep the vents clear of obstructions
  • Avoid using the computer in very dusty environments

You can’t stop your computer from getting slower

Computers slow down over time - that’s inevitable. You can delay the process through careful management of the apps you use, and by reinstalling the operating system from time to time.

The only computers that don’t slow down are usually running one or two apps, probably because they’re performing a single task over and over. These computers can run for years. 

However, if you’re using a computer day after day, for a mix of different jobs, it will start to slow down.

Read our guide to buying a used laptop.