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Yes, Your Security Software Might Slow Down Your Computer – What to Do About It

When you think about it, the security software on your computer, and specifically the anti-malware tools, have to do a lot of work.

So much so that the work might impact your computer’s speed — perhaps for a while, perhaps constantly.

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Security software can slow down your computer, it’s true. You can select tools with a reputation for minimizing their impact, as well as choosing times and options that minimize the impact when you’re trying to get work done. The role of security software is important, and taking the time to make sure it doesn’t get in your way is too.

Scanning takes time and resources

Slowdowns ComingWhen we ask our security software to perform a full scan, it needs to read and examine the contents of every single file on our computer. Even when restricted to those file types that most commonly contain malware, that adds up to thousands and thousands of files.

On top of that, we’re asking the anti-malware tool to check each file against its entire database of known malware. That could include hundreds of thousands of different characteristics or patterns.

The result? Thousands of different files on our machines are getting checked against hundreds of thousands of different known malware patterns.

That’s a bunch of work. Naturally, exactly how much impact the scans have on performance vary based on which anti-malware tool you’re running and how fast your machine is. In an ideal scenario, the scan operates without notice, but reality is somewhat different.

Slow for “a while”

The most common scenario I hear about is a computer that’s slow for “a while” after it’s first turned on or logged into.

This is often the result of security software performing a scan (as requested) immediately upon booting. Once the scan is complete, the computer returns to normal.

And, of course, some tools are better at minimizing their impact than others.

What to do

There are a few options to explore if you find that your security software is impacting your computer’s performance when you’d rather it didn’t.

  • Try to pick an anti-malware tool that has a reputation for not being particularly disruptive. This is one of the factors heavily impacting my recommendation of Windows 10’s Windows Defender built-in tool.
  • Have the malware tool perform its automated full scan at a time you don’t typically use the computer. This means possibly leaving the computer on when you’re not normally using it and scheduling the scans to happen then. The most obvious choice is to leave it on and run the scans overnight.
  • Look for options in the anti-malware tool to adjust its performance impact. Some allow you to adjust the amount of CPU used during a scan; some will pause a scan if the computer begins to be used; and others will delay the scan completely until the computer is idle.

Security software is important. I’d even go so far as to say that it’s a critically important part of keeping you safe. That safety, though, comes at a cost: the tool needs the time and resources to do the job we ask it to do. By picking and choosing the right tool and the parameters under which it runs, we can minimize the impact to the point of it not being an issue at all.

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5 comments on “Yes, Your Security Software Might Slow Down Your Computer – What to Do About It”

  1. Backup, Backup, Backup….This is the most important defense against malware.
    But as usual, you ignored the need to have a minimum of 30+ day old Backup to Restore, as some of the malware are designed to be active after 30 days.

  2. In my nearly 40 years of PC experience (I started young), malware scans usually take a relatively short amount of time — as opposed to anti-virus scans. Unless you are constantly at your computer, there’s no need to leave your computer on overnight to run these scans. You can schedule a malware scan to run during your lunch time (heck Malwarebytes takes less than 10 minutes and I’ve got 3.5 million files of apps and data on my computer). Antivirus scans take a lot longer – but I’ve found we can just schedule them to run during dinner time with no problem.

    • I’m not quite sure I understand the difference here … malware refers to all malicious software, of which viruses are a subset. So an antivirus scan would scan less than an antimalware scan.

  3. Thank u, Leo. Some users try to use a few different antivirus and malware apps at the same time with the belief that this will help. They do this with the thoughts that their system is slow due to a virus or malware issues. Yes, you can use more than 1 piece of software but my advice is to use it for scanning only and turn it off when not in use. Windows Defender does a very good job
    Leo, your advice about how to recognize issues, and what to do about them is very valuable. Also, some of your readers gave great advice as well, especially about backups. Backing up is great advice, even if you do not have issues


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