Four characteristics of computer speed.
Some time ago, I was at a friend’s home to diagnose a problem he was having with his Windows 10 computer.
It had become almost unbearably slow.
He had called to say the problem had begun after some kind of pop-up message to “call this number” that could not be dismissed, followed by mis-click of some sort on Microsoft Edge, at which point the disk light began flickering continuously and the system came to a crawl.
Fearing the worst, I advised him to turn off the machine until I could get there and see it in person.
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Why a computer might be slow
Your computer’s speed can be impacted by the speed and usage of four different characteristics: CPU, disk, internet, and RAM. Each can cause computer slowness, yet each will have different causes if it does. Even if examining these four aspects doesn’t turn up a suspect, very often they’ll confirm the eventual cause of the slowdown.
The characteristics of speed
There are four separate characteristics contributing to how fast or slow a computer “feels” or appears to work.
- CPU: its speed and how programs are currently using it
- Disk: its speed and how frequently it’s being accessed
- Internet: its speed and how much data is being transferred
- RAM: the amount available and the amount in use
Whenever I encounter a machine reported as being “slow”, I look at each of these in turn to help narrow the problem.
What follows is (of necessity) an oversimplification of the process I used to diagnose the problem.
CPU: the processor
Your computer’s CPU is its “brains”. Its job is pure calculation, but those calculations involve everything from crunching numbers to telling your computer’s hardware what to do. If it’s too busy crunching numbers, it might have little time left over to accept keystrokes from your keyboard, read and write data on your disks, or update your screen. As a result, your computer is “slow”.
The CPU can be completely busy for many legitimate things, like performing encryption, processing video, or even calculating a complex spreadsheet. Less legitimately, the CPU can be fully consumed by program bugs, or even malware.
Malware performing encryption — i.e., ransomware — was at the top of my list of concerns for my friend’s computer. I opened Task Manager and looked at CPU usage, but it showed nothing out of the ordinary.
The CPU was doing next to nothing, yet the computer was definitely slow. That didn’t rule out ransomware, though. My concern remained.
Disk: the storage that sticks around
Your hard disks are where your files and other things — like Windows itself and the programs you use — are stored.
Hard disks can be small or large, fast or slow — and many variations and combinations in between. Whether yours is a hard disk (spinning metal platters coated with magnetic material) or a Solid State Drive (which use electronic circuitry instead), it takes time to read information from them or write information to them.
Your hard disks can be occupied simply because your computer is busy reading or writing a large file (or many little files). Since the disk can do only one thing at a time, all that time reading or writing anything can get in the way of reading or writing anything else. The system appears to slow down because it is waiting for some of that reading or writing to complete.
The reason I remained concerned about ransomware is that if malware was in fact reading, encrypting, and then writing all the files on my friend’s hard disk, it’s possible the disk would be at the choke point: the CPU would spend only a fraction of its time actually encrypting compared to time spent waiting for the hard disk to finish reading or writing whatever came next.
That the disk light was flickering, indicating near-constant disk activity, did nothing to alleviate my concerns. So I used Task Manager to see what the disk was doing. Sorted by disk activity, nothing really stood out.
Yet the system was slow. My thoughts were shifting away from ransomware and more towards “What the heck?”
Internet: transferring data to and from online services
Your internet connection is your computer’s connection to the outside world.
Often, what we call our computer being “slow” is really just our own impatience. It takes time to transfer data to and from the various servers and services you use online. Your internet connection has a maximum speed determined by your ISP and the plan you purchase from them.
Only so much data can be transferred at a time. If your computer is attempting to transfer more than capacity allows, someone’s going to be left waiting. If that’s you, waiting for a webpage to load, it’ll feel slow. It’s not your computer; it’s the speed of your internet connection slowing things down.
The problem, of course, is that there’s a lot more going on than just you and your web browser. All the computers in your home probably share that same internet connection, and all of them have a variety of things happening online, from other people using their browsers and other services to software downloading automatic updates. It all comes out of your single, shared internet connection.
My friend didn’t have a lot else happening online in his home, but that disk light was still flickering. I was wondering if some different malware was at work, perhaps downloading files or acting as some kind of spam bot.
Back to Task Manager I went, this time sorting by network activity.
Again, nothing out of the ordinary. Edge was there, doing its thing. Multiple instances, but none generating enough traffic to move the needle. That was to be expected… or so I thought.
RAM: short-term memory
RAM, or Random Access Memory, is your computer’s short-term memory. It’s where running programs and where the data they’re working on resides, and it’s what gets instantly erased when you turn off your computer.
Your computer only has so much RAM, but that doesn’t prevent Windows from trying to use more. Using a process called virtual memory, Windows can simulate having more RAM than it actually does by moving (reading and writing) some of what’s in actual RAM to the hard disk to make room for newer requests.
If your computer has enough RAM, virtual memory is virtually never used. Since accessing RAM is significantly faster than accessing a hard drive, if your computer does find itself bumping into memory limits and using virtual memory, adding real RAM is one of the fastest and most effective upgrades you can get.2
Back at Task Manager, this time I sorted by memory usage.
Once again, everything looked normal.
It was starting to look like I’d struck out.
Let’s blame Edge
None of the items I looked into above seemed out of the norm. But, to be honest, the computer didn’t seem abnormally slow. It wasn’t the newest of machines, but it seemed adequate for my friend’s needs.
I hadn’t seen the “call this number” pop-up message that my friend had seen, so I wasn’t seeing exactly what he saw, either.
Normally, he uses Chrome, but in the excitement resulting from that pop-up, he had somehow clicked on the Edge icon in the taskbar. So I did too.
Then it started again.
And again and again and again.
Within a few minutes, the taskbar slowly filled up with instances of Edge. If you weren’t paying attention to your taskbar — and it’s totally understandable why you might not — you might not even notice it happening.
Each copy, or “instance”, of Edge used up a little more RAM, until eventually, virtual memory was called for. Windows dutifully responded by swapping things to and from disk, allocating more and more virtual memory, until all it was doing was managing more and more copies of Edge.
The system slowed to a crawl. Left to its own devices, eventually the system would become completely unusable.
I couldn’t close Edge fast enough to prevent it from opening another instance of itself, so I used Task Manager to kill as many as I could, leaving just one that had already done the “start another copy” thing.
I suspected the homepage setting had somehow become corrupt. You can set Edge to open one or more webpages automatically when it starts, and I suspect this was somehow confused: one of those pages caused a new instance of Edge to open, where it repeated the process of opening webpages automatically (which opened another copy of Edge, which opened pages automatically, ad infinitum).
I reset Edge’s “Open Microsoft Edge with” setting (via the ellipsis menu, “Settings” menu item) to be “Start page” – Edge’s own default start page. (This was the old pre-Chromium version of Edge).
I closed Edge, restarted it, and all was well once again.
The takeaway: what happened?
I have no idea what happened.
And that’s a very practical, pragmatic reality of what it means to resolve computer problems. Occasionally, the best you can hope for is that the problem goes away — without really understanding why it appeared in the first place.
But that doesn’t prevent me from hypothesizing.
My guess is that the “call this number” pop-up (you should never call the number, by the way) was nothing more than a persistent and annoying webpage (or pop-up within a webpage). Perhaps it was a malicious ad; perhaps my friend accidentally clicked on a link he normally wouldn’t have, or perhaps he mistyped a URL into his browser’s address bar. While it got our attention, it was probably a red herring.
Since he doesn’t regularly use Edge, it’s unclear how long its start-page configuration had been confused, lying in wait to confound us. Not being able to trace that back to a specific time or event meant it would be impossible to know exactly how or why it happened. I was so focused on fixing it that I didn’t examine the “broken” setting first.
The good news, however, was that understanding the four characteristics of what it means to be “slow” not only gave me a framework to examine the system, but helped confirm the diagnosis when we finally discovered something amiss.
When faced with persistent, unexpected slowness in your computer, take the same approach I did above: check CPU, disk, internet, and RAM usage, each in turn, to try to determine what specific aspect of your system is responsible for the slowness. With that data in hand, most often you’ll be able to identify a culprit. Even if not, as in my case, understanding the relationship of those four can also help you confirm a subsequent problem diagnosis.
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Footnotes & References
2: Actually, Windows will make more use of more RAM, so it’s often an effective upgrade regardless of whether you’re using virtual memory or not — but that’s outside the scope of this article.