Why the computer is slow and what you can fix yourself

“My computer has got slow” is probably what I hear second most often, after the internet. The age of the machine is rarely the culprit. Almost always it is one of these.

A full disk

When only a few gigabytes are left on the disk, Windows has nowhere to put temporary files and everything crawls. Open This PC and look at the bar under drive C. If it is red, you have found your cause.

The quickest clean-up: type Disk Cleanup into Windows search, run it and tick everything except the items you are unsure about. Then empty the Recycle Bin — people often have tens of gigabytes sitting in there.

Programs that start with the computer

Every program you install likes to launch itself at startup. After a few years there are twenty of them running and the computer takes minutes to wake up.

Press Ctrl + Shift + Esc, switch to the Startup tab and go through the list. Leave alone anything you do not recognise. But things like Spotify, Steam, Skype or driver updaters can happily be disabled — you can start them by hand when you need them.

A browser with thirty tabs and five add-ons

If it is only browsing that is slow, the computer is not at fault. Every open tab holds on to a chunk of memory. And browser add-ons, especially the ones promising coupons or a speed boost, tend to be dead weight.

Try opening the browser in a private window — add-ons do not run there. If it is suddenly quick, you know where to look.

An old spinning hard disk

This is the one of the four you cannot fix at home. Computers older than roughly eight years tend to have a traditional spinning disk. It is several times slower than today's SSDs and no amount of cleaning will change that.

The good news: swapping the disk for an SSD is the cheapest way to turn an old laptop back into a usable machine. It costs a fraction of a new computer and the difference is immediate. The data can be transferred across, so you lose nothing.

What not to do

• Do not install “optimisers” and “registry cleaners” from the internet. At best they do nothing; at worst they add advertising.
• Do not reinstall Windows as a first step. Usually it is not necessary and you lose your settings.
• Do not buy a new computer until you know what is holding the old one back.

If you are not sure which of the four it is, give me a ring. It takes a few minutes to tell, often remotely.