Why your computer is slow, and what actually fixes it
"It's got slow" is the most common thing we're told, and the cause is nearly always one of a handful of things. None of them is fixed by the cleaner software advertised alongside the problem.
Here's what it usually is, roughly in the order we find it.
An old-style hard drive — the biggest single cause
If the machine takes a couple of minutes to reach the desktop and the drive light is solid, it almost certainly has a spinning hard disk rather than an SSD.
Replacing it with an SSD is transformative in a way no software tweak comes close to: boot times drop from minutes to seconds and everything feels new. On a machine that's otherwise sound, it's comfortably the best money you can spend — and cheaper than a replacement computer.
Not enough memory
4GB is no longer enough for Windows 11 and a browser with a dozen tabs. 8GB is the sensible minimum, 16GB comfortable.
You can check in Task Manager: if memory sits above 80% while you work normally, that's your bottleneck. Adding RAM is inexpensive on most desktops and many laptops, though some newer laptops have it soldered in and can't be upgraded.
Too much starting with Windows
Years of installed software each add something that launches at startup and keeps running.
- Open Task Manager, then the Startup tab, and disable what you don't need — printer helpers, updaters, chat apps
- Leave antivirus and anything to do with drivers alone
- Uninstall software you genuinely don't use rather than just stopping it starting
- Trim browser extensions; a browser with fifteen add-ons is a slow browser
Heat and dust
When a laptop gets hot, it deliberately slows down to protect itself. A machine that's fast for ten minutes and then sluggish, with the fan roaring, is overheating rather than short of power.
Clogged vents and dried thermal paste are the usual causes. A proper clean and repaste restores full speed and is far cheaper than replacing the machine — and it's routine workshop work.
A full drive, or a failing one
A drive with less than about 10% free space slows noticeably, because the system has nowhere to work. Clearing space often helps immediately.
But if slowness comes with freezes, clicking noises, files that won't open or errors on shutdown, that's a drive on its way out. Back up now and get it checked — the slowdown is a warning, not the problem.
What doesn't work
Registry cleaners, "PC boosters" and driver updater tools do essentially nothing useful, and a good number of them are adware. If a program found hundreds of problems and wants payment to fix them, uninstall it — it is part of the slowness, not the cure.
One genuine exception: keeping Windows and drivers up to date through Windows Update itself does help, particularly graphics drivers.