Sunday, October 1, 2023

Why Is Avast Using So Much CPU?



Avast is a popular antivirus app that protects your computer and other devices from malicious software. If you have a Mac or smartphone, you are much less likely to encounter such software than on a computer. So, if you are using Avast on your computer, you may have noticed that it is using a lot of CPU power when it’s running in the background.

If your computer hardware is getting old, this can have a huge impact on your computer’s speed. You might have noticed that your programs take forever to load, there is a huge delay between when you click on something and when something happens, and your programs are generally slower after installing Avast.

Thankfully, there are a lot of steps that you can take to significantly reduce the impact on performance that Avast has. Let’s take a look at why Avast uses a lot of CPU and how to mitigate it.

Why Is Avast Using So Much CPU?

Avast uses a lot of CPU power, RAM, and other resources because it has to scan all files in your computer one by one. The background processes and other real-time operations that take place when your computer is turned on are very demanding. This is great for security, but not for performance.

Another possible reason is that your system settings are not configured properly. It could also be a problem with Windows registry entries. You will find the solution to these problems below.

You might be inclined to uninstall Avast because of the performance hit but remember that the Internet is full of viruses, adware, spyware, and other malicious software. Some of them can steal your credit card details or wipe all your data. After all, you don’t want to lose all your work files and cute photos of your family. So, do all the following steps to reduce Avast’s high CPU usage.

How to Check Avast CPU Usage?

There is the possibility that it isn’t Avast that is causing your CPU usage problems. It could be a different problem entirely. The easiest way to check if Avast is using a lot of CPU is through Windows’ built-in Task Manager.

Here is how to check it:

  1. Open Task Manager by pressing Ctrl+Alt+Esc or Ctrl+Alt+Delete and choosing Task Manager. You can also right-click on your taskbar and open Task Manager through the pop-up menu.
  2. On the “Processes” tab, you will see all programs that are running in the background at the moment and how much CPU, memory, and other resources they use. Find Avast on this list and check the CPU %. Hint: you can sort the programs by CPU usage or by name if you click on those columns.

If Avast is using 20% CPU or more, then you have a problem with it. Otherwise, it could be some other program on the list causing it. If you have established that Avast is indeed the problem, here is how to fix it.

How to Fix Avast’s High CPU Usage

1. Old Version of Avast

Let’s get the most obvious possible problem out of the way first. Avast is updated frequently for a few different reasons. First, new malware, viruses, and spyware are constantly popping up. Sometimes, these malicious programs are different from the pre-existing ones, so Avast developers have to add new security features to protect your computer from them.

There is always something to improve and fix. Software is extremely complex, so there are always bugs popping up here and there. There is not a single program out there that is completely bug-free. Even if such a program existed, a new Windows update could cause some trouble.

The performance and design will need to be updated occasionally too. If you are using a very old version of Avast, you could reduce bugs and improve performance by a lot if you simply update the program. Thankfully, updating is pretty easy and you can do it from the program, so there’s no need to download and install it again.

2. Incorrect System Settings

This is another reason why Avast could be using so much CPU. Incorrect system settings and problems with Windows registry entries can cause errors and bugs that make the CPU usage spike. Problems with system settings happen because of several different reasons. Windows updates or any changes that you do to your hardware (even overclocking) can cause them.

The easiest way to fix these issues would be to repair or reinstall the program. If you want to repair it, here is how you can do it:

      1. Go to Start and type “Add or remove programs”, then click on the gear icon to open it. Alternatively, you can find this in Windows 10 settings or in the Control Panel. You may find it under the name “Uninstall or change a program”.
      2. Locate Avast on the list, click on it, and choose “Uninstall”.
      3. Avast’s uninstall wizard will pop up with a few options. Choose repair and wait for the process to finish.
      4. After repairing, restart your PC and check if the problem is gone.

If this solution did not help you, then it’s time to move on to the next one.

3. Check Avast Screen saver Scanning

Avast has a nice feature that recognizes when your screen saver is on, which means that your computer is not being used at the moment. Avast uses this time to scan and remove suspicious programs, but it can sometimes get bugged and continue working even after your screen saver is not running. This screen saver scanning causes high CPU usage.

Here is how to fix the issue:

      1. Right-click on any file on your computer and click Avast’s “Scan selected items for viruses” option.
      2. A new window will pop up that shows scan results, including those that are currently running in the background.
      3. Find “Avast Screensaver scan” and press “Stop”.
      4. Check if the issue has been resolved.

If the problem persists, here are a couple of more extreme solutions.

4. Use a Command Prompt Tweak

This solution will essentially disable background processes that Avast has to perform, which means that you will have to manually scan your PC for viruses. Because of that, this solution is also one of the more effective ones.

Here’s how to do it:

      1. Open “Start”, type “Command Prompt” or “cmd” for short, right-click on it, and click on “Run as administrator”.
      2. Copy and paste this command (without quotation marks) that will take you to the Avast folder: “C:\ ProgramData\AvastSoftware\Avast”.
      3. Open “avast5.ini file” and insert the following: “[GrimeFighter]: ScanFrequency=999”.
      4. Save and restart your computer.
      5. Check if the CPU usage problem is gone.

If this didn’t fix your CPU usage, then it could be a problem with a component. Check the next step for more details.

5. Remove the Avast Cleanup Tool (or Any Other Avast Component)

The Avast Cleanup Tool is essentially a real-time scanner that keeps your computer free from malware. However, it also uses a ton of CPU and RAM to do so. Removing this tool is very likely to fix your problem and this is how it’s done:

      1. Open Avast.
      2. Go to “Settings” and navigate to the “Components” tab.
      3. Click the arrow on the right of the component tab to expand it.
      4. Locate “Avast Cleanup”, click “Uninstall a component”, and confirm it.
      5. Restart your computer.
      6. If this did not fix it, do the same steps from above for “Behavior shield”, “File system shield”, and other components. Do it one by one to identify the problem. Make sure to re-enable other components once you find the component that is causing high CPU usage.

Most users that have had problems with high CPU usage caused by Avast claim that this solution helps. Some say that the Web Shield and the Real Site caused the problem, others report that it was the Anti-Spam feature. Your mileage may vary here.

Remember that disabling these components will have an impact on your security, so decide for yourself which components are worth keeping. If you disable real-time scanning features, you should then do manual scans now and then to ensure that your data is safe.


Avast, just like any other antivirus program, has to perform background processes and scans to keep your computer clean and secure. Sometimes, these processes can cause issues with high CPU usage, especially if your computer hardware is not very powerful. Even then, scanning every single file takes a lot of processing power and you will notice a drop in performance.

These solutions worked for most users that have had CPU usage problems when using Avast. You should first try to do less severe solutions, such as updating or repairing. If that does not fix it, you can then tinker around to fix Avast’s high CPU usage.

Remember that disabling components in Avast or changing the scan frequency will make your computer less secure, so you should do frequent manual scans to keep your computer clean and your data safe.

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