Why Is My Machine Slowing Down?


Slow machines represent one of the largest sources of questions to Ask Leo!

Perhaps when you purchased it, your computer ran like a champ and quickly did everything you needed. Now … well, not so much. Perhaps it takes forever to boot. Or starting applications is slower than molasses. Or maybe the machine just acts sluggish when you try to use it for just about anything.

Regardless of the specifics, the underlying theme is simple: it’s slow.

There are many, many reasons that a machine could slow down.

I’ll list a few of the most common reasons here, along with some advice on what steps to take.

It’s a slow machine

An assumption I’m making here is that it’s your entire machine that is slow, not just one or two applications.

For example, if Internet Explorer has slowed down while the rest of your software runs just fine, you need a different approach than what I’ll outline here, focusing on the specific applications that are behaving slowly. Perhaps some of the solutions may be the same, but arriving at those solutions and choosing one will depend on investigating the issue with that specific application.

Nope. Here, we’re talking about a slow computer.

Sudden slowdowns: Malware comes to mind

If the slowdown is sudden and severe, the first thing that comes to mind these days is malware.

Different types of malware do different things, but they also behave differently on different machines. One of the symptoms of malware can be a suddenly slow or sluggish system.

Your anti-malware tools are your first line of defense. Make sure they’re up to date, and run scans using both your anti-virus tool and anti-spyware tool (assuming you’re using separate tools).

Naturally, I have recommendations for anti-malware tools.

Sudden slowdowns: A program run amok

Another step I take when my machine seems to be slowing down, particularly if it’s sudden and unexpected, is to fire up Process Explorer. Very often, the source of a system slowdown can be attributed to a single program running on your machine that is attempting to use all available processing resources. When that happens, other programs (often including Windows itself) aren’t able to respond to your actions as quickly.

How Do I Find Out What Program Is Using all My CPU? walks you through the steps of using Process Explorer to identify any processes in this state.

Similarly, a program that’s using the disk heavily (i.e. the activity light isn’t even flickering, it’s just on), or even using the network heavily can manifest as a slow system. I Have Constant Disk Activity, and I Don’t Know Why. How Can I Tell What Program Is Doing It? and How Do I Monitor Internet Activity and See Who’s Using It? will help you identify those culprits, if present.

Sudden or gradual slowdowns: Impending hardware failure

This isn’t as common, but it definitely does happen.

We normally think of most hardware failures as sudden and catastrophic. Sometimes, they’re a little less catastrophic than we think.

For example, if a sector on a hard disk is going bad, that may first manifest as a slowdown whenever that sector is accessed. The disk drive will try multiple times to read a marginally bad sector before giving up, and that takes time. If multiple sectors are affected (which is common if it’s an area on the disk media that’s been damaged, for example), then this might be happening for more than one sector, and that time adds up. The system keeps working because the sectors aren’t so bad that they actually fail, but they take additional time to be read because they’re going bad.

Back up, of course. Impending failure can quickly become actual failure and data loss.

In situations like this, I typically start by running CHKDSK /R, and/or SpinRite to diagnose and possibly repair the hard disk in question.

Gradual slowdowns: Too much stuff

In my experience, the #1 cause of a system gradually slowing down over time is that it’s being asked to do more and more and it’s trying to run too much software simultaneously.

Generally, folks find themselves in this situation after installing software on their machine that includes a component that always runs. Over time, there’s so much running on the machine even when it’s not in use that when it is in use, there’s not enough computing power left over to run the programs quickly and efficiently.

Examples of software that might get installed over time? Webcam software after getting a webcam, instant messaging programs, Skype, Dropbox, Evernote, screen capture utilities, TrueCrypt, and so on. There are many possibilities, and that doesn’t even take into account the ubiquitous software update checkers and quick loaders that so many software manufacturers are fond of building to run all the time.

There are two approaches to resolving the “too much stuff” scenario:

  • Run less stuff. Review the list of software running on your machine when you’re not doing anything (Process Explorer will help) and question everything you’ve installed. Uninstall everything you don’t really need.
  • Beef up your computer. It’s a common adage that adding RAM to your computer is one of the quickest ways to speed it up, and this is why. If RAM is a constraint for the software you’re running, your computer will absolutely slow down. Adding RAM to your system, if it’s possible, fixes that.

Gradual slowdowns: Fragmentation

It’s not the common problem that it once was (particularly with SSDs, where this doesn’t apply, and Windows 7 and later, which defrag automatically), but it’s possible your hard disk has become fragmented. All recent versions of Windows have built-in defragmenting tools.

In Windows File Explorer, right-click on your hard disk drive (normally C:), select Properties, and click on the Tools tab — there you’ll find the disk defragmenter. It’s a good tool to run periodically, although how often will vary depending on your computer usage.

Gradual slowdowns: Updates

In a sense, this falls into the “too much stuff” category, but applies even if you haven’t made a single change.

It’s commonly understood that systems tend to get bigger over time. That’s more or less the nature of software evolution and our expectations of ever-increasing functionality and support.

While we normally associate that with major version updates (i.e. Windows 7 was larger than Windows Vista), it can actually happen — slowly — at the system or application update level as well.

Years of updates slowly increase the resource requirements of your operating system and applications. Particularly if your system is already somewhat marginal, that increase can be enough to impact your overall performance.

Note that I’m not talking about files left behind after an update (unless, of course, your hard disk is filled to capacity), but simply the scenario where the patched version of application “A” might need ever so slightly more RAM than before. Repeat that for all the applications that you have installed and the updates your system receives, and over time it adds up.

Once again, adding RAM can help if this is the case.

Originally published as Why Is My Machine Slowing Down? on Ask Leo!