A man holding his head in his hand while perched over a laptop.

You know the feeling: Your once-snappy Windows laptop now takes ages to do simple things such as opening folders and saving files, leaving you wondering what’s going on.

What can you do?

There are many reasons a laptop may suddenly slow down, including lack of memory and the presence of computer viruses, or malware. So there’s no single answer to that question. 

“If the memory or storage space is taxed, it can result in a slowdown in performance,” says Antonette Asedillo, who oversees computer testing for Consumer Reports. There’s also a new type of malware that hijacks your computer to generate cryptocurrency without your knowledge or consent. 

More on Laptops

Regardless of the reason, the end result is the same. Your laptop suddenly devolves from a fine-tuned thoroughbred to a plodding plowhorse. And that’s certainly not what you signed up for when you bought the device.

But you don’t have to settle for that painfully slow ride. Here are some ways to identify the issue and solve it.

Free Up More Memory

As Asedillo points out, insufficient memory is a common culprit.

When working on a file, be it a Word document or World of Warcraft, your computer places the data on a memory chip, also known as RAM. There’s no problem if the file is small enough for the memory chip. But if it’s too big, your computer has to compensate by relying on your computer’s hard drive.

“If you have 8GB of memory and you open up a 25GB video, obviously the entire video is not going to fit into memory,” says Richard Fisco, an electronics testing program leader at Consumer Reports. “So what the computer does is write it to your hard drive, which is a lot slower than main memory.”

If you mostly use your laptop for light tasks such as editing Word documents and going to Amazon, Facebook, and Gmail, you can probably get by with 8 gigabytes of RAM, maybe even the 4GB that many Chromebooks ship with. But if your needs are more advanced—requiring multiple apps from the Adobe Creative Suite to be open at once, for example—you’re going to want at least 16GB.

So how do you speed things along? By freeing up memory.

To see how much memory you’re using, press down on the Alt, Control, and Delete buttons at the same time, then click to open the Task Manager. To increase the available memory, close any programs you don’t need—perhaps you forgot to quit Adobe Lightroom after importing your latest batch of vacation photos.

Take a quick look at your web browser, too, whether that’s Google Chrome or Microsoft Edge, because every open tab eats into memory. One tip: Instead of keeping a dozen tabs open at once, rely on your browsing history to keep track of the websites you’ve been to.

Defrag the Hard Drive

You might also considering defragmenting your hard drive, which optimizes your files so that they can be found quickly.

Fragmentation affects only traditional hard disk drives, which are sometimes referred to as HDDs. It does not affect newer solid-state drives, or SSDs, because those don’t contain moving parts.

In an HDD, the disk physically spins as data is written and read. As time goes by and data gets spread across the disk, it may take longer for the header to locate the data.

To defrag, start by typing “defrag” (without the quotation marks) into the search bar/Cortana, then select the C drive and Optimize. Note: The process can take several hours depending on how large and how fragmented your hard drive is.

“Start it off,” Fisco says. “And let it go.”

“What defragging does is say, ‘Oh, I’ve got this piece of a file—what does it belong to?,’” Fisco says. “It can tell that it belongs to this, this, and this, and put all the elements together. So now they’re not all over the disk and it can read them really quickly.”

Check for Malware

In the past year, a new malware has emerged that allows cybercriminals to take over your computer’s processing power to generate bitcoin and other cryptocurrencies.

Malware, of course, is a sort of catchall term that describes malicious software (hence, “malware”) that can do things like steal your usernames and passwords or lock your files until you pay a ransom.

According to computer security firm Skybox Security, the malicious software is now more popular among digital thieves than ransomware, constituting nearly one-third of all cyber attacks in the first half of 2018.

If the malware ends up on your computer, it can monopolize your processor, grinding every other operation, from flying through an Excel spreadsheet to digging into a YouTube rabbit hole, to a halt.

To determine whether your device might be infected, return to the Task Manager (press Alt, Control, and Delete buttons at the same time and click Open) and look for a website or application that’s claiming 80 to 100 percent of your CPU load—these percentages are clearly labeled in Task Manager. That’s a pretty good sign that you may need to consider some form of antivirus protection.

There’s no fully guaranteed solution—malware threats are constantly evolving—but Bitdefender and Norton Security provide two of the top-rated antivirus software options in our ratings.

And while we haven’t tested them in our labs, a free, open-source web browser extension, such as No Coin or MinerBlock, may also block websites from stealing your CPU cycles. Just keep in mind that cybercriminals have been known to deliver malware in the guise of antivirus protection. So before you go that route, try to verify that you’re dealing with a reputable source.

Beware Peak Internet Hours

In some cases, the sudden slowdown in performance has nothing to do with your laptop at all but instead involves heavy activity on your local WiFi network.

The root cause could range from one of your kids deciding to download an episode of “Game of Thrones” from a shady BitTorrent site (which is a bad idea, by the way) to heavy internet traffic in your local area, which Fisco says can be a problem for consumers who get their broadband service delivered by a cable company, particularly during peak television-viewing hours.

“Don’t say, ‘Oh, my PC is slow,’ when it’s just slow internet,” he says.

What do you do? Wait it out, of course, which might not be so bad, unless every house in your subdivision suddenly decides to stream the latest stand-up comedy special on Netflix.