Quick wins for a faster PC:
Clear out junk files and repair common Windows errorsFree Scan →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Repair Windows errors before they cause bigger problemsFix Now →To reduce antivirus-related CPU load without giving up routine protection, schedule quick scans instead of full scans, run scans at less disruptive times, and—where Microsoft Defender is centrally managed—lower scheduled-scan priority or its CPU usage limit. Keep real-time and cloud protection on. There is no established, universal antivirus setting that reduces memory use across products; first identify which product and process is using resources.
Start by identifying what is using resources
Antivirus settings vary by product and configuration. Check which security product is installed and which process is consuming CPU or memory before changing settings. The Microsoft performance guidance recommends diagnosing Defender performance issues rather than assuming every slowdown has the same cause: Microsoft Defender for Endpoint performance troubleshooting.
The documented controls discussed here chiefly affect scanning behavior and CPU competition. They do not establish a general memory-saving switch or a comparable memory reduction across vendors.
Use routine scans that match the task
Microsoft Defender: prefer scheduled quick scans
Microsoft recommends scheduled quick scans alongside always-on real-time and cloud protection. Its guidance says most users do not need scheduled full scans; it also states, “In general, there’s no need to schedule a full scan, and most users never need to manually run full scans.” See Microsoft Defender Antivirus full scan considerations and best practices.
#1 Best Overall
A quick scan is the more appropriate routine scheduled option in this guidance. A full scan may take longer and use system resources while it runs, so avoid scheduling one routinely unless a specific need or troubleshooting instruction calls for it.
Choose a less disruptive scan time
If scans interfere with work, schedule them for a time when the PC is less heavily used, if your product or administrator-managed policy offers scheduling. This shifts the workload rather than eliminating it, and the available controls differ among products.
Rank #2
Lower Defender scan competition on managed PCs
Microsoft documents administrator or policy controls for reducing scheduled-scan CPU competition: enable low CPU priority for scheduled scans or reduce the scan CPU limit. These settings can make scans take longer. The CPU percentage guidance is for the scanning engine; it is not a guaranteed hard cap on the computer’s total CPU use or a memory limit. They may not appear as simple controls in the Windows Security consumer interface. Details are in Microsoft’s Defender performance troubleshooting guidance.
Use exclusions only for a specific, trusted conflict
An exclusion can stop a product from repeatedly scanning a particular file, folder, file type, or process, but it also reduces scanning coverage for the excluded content. Use one only when you have identified a trusted item that is causing a real scanning conflict, and keep its scope as narrow as possible.
Free tools Windows power users keep installed
One-click scans. No signup required.
In Windows Security, exclusions are managed under Virus & threat protection > Manage settings > Exclusions. Microsoft says Defender exclusions apply to real-time scanning; scheduled Defender scans or other antimalware products might still inspect the item. See Virus and Threat Protection in the Windows Security App.
Exclusion behavior differs by vendor. McAfee says excluded files or apps are not scanned by its real-time, on-demand, scheduled, and command-line scanners. Check the instructions for the installed product before applying an exclusion: McAfee: Exclude files from virus scans on Windows and macOS.
Rank #4
Keep real-time protection enabled
Turning off real-time protection is not a sensible routine performance setting. Microsoft warns that files opened or downloaded while Defender real-time protection is off are not scanned at that time, and describes the off state as temporary; it turns back on after a short while. McAfee likewise warns that disabling real-time scanning leaves the PC exposed to threats. See Microsoft’s Windows Security guidance and McAfee’s real-time scanning options.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Do not assume a faster scan uses fewer resources
McAfee’s Fast Scan documentation says that its faster full scan uses all available system resources, including CPU and memory. That is a product-specific example, not a rule for every antivirus: a mode designed to finish faster can increase resource use while it runs. See McAfee: How to run a Fast Scan in Windows.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
