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Windows 11 includes tools for scanning for malware, filtering network traffic, checking selected device-health indicators, and freeing system-drive space. They answer different questions: a clean scan is not a full PC diagnosis, a green health report does not guarantee trouble-free hardware, and cleanup is not a universal performance fix. Here is where to find each tool, what it covers, and what to do when a problem persists.
What Windows Security covers
Open Start, search for Windows Security, and open the app. Its sections provide access to Microsoft Defender Antivirus, firewall and network protection, app and browser controls, device security, and other security settings. Availability and labels can vary with Windows version, device capability, locale, and administrator policy. Microsoft describes the app as a comprehensive security solution integrated into Windows in its Windows Security App Overview.
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Security is a collection of protections, not a single scan. Antivirus checks for threats; the firewall filters network traffic; other controls address areas such as apps and device security. A green status does not mean a PC is immune to threats.
Run a scan or check a file
In Windows Security, open Virus & threat protection and choose a quick scan to check common locations. For a suspicious individual file or folder, use File Explorer: right-click it and choose Scan with Microsoft Defender. On Windows 11, this command may be nested under Show more options. Microsoft’s guidance is in Stay protected with the Windows Security app.
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If another antivirus app is installed and turned on, Microsoft Defender Antivirus turns off automatically. Check which protection is active before installing another antivirus product; adding a second product is not a prerequisite for using Windows Security’s other features.
Keep the firewall on and handle blocked apps narrowly
Open Windows Security and select Firewall & network protection. The page shows the network profile in use and lets you view settings for domain, private, and public networks. A public Wi-Fi network is generally less trusted than a private home network, so pay attention to the active profile. Microsoft’s instructions are in Firewall and network protection in the Windows Security app.
If a legitimate app cannot connect, Microsoft advises allowing that app through the firewall rather than turning the firewall off. Disabling the firewall removes a layer of network filtering instead of addressing access for just the app.
What Device performance & health can tell you
In Windows Security, open Device performance & health. When opened, the page runs a scan and reports on selected areas: storage capacity, battery strain on devices with a battery, app or software failures and updates, and the Windows Time service. Microsoft documents the feature in Device performance and health in the Windows Security App.
- Green check: no recommendation is currently shown for the areas the report checks.
- Yellow indicator: attention is recommended; read the finding and follow its suggested next step.
- No page visible: an organization policy may hide this view on a managed device.
This is a selected-issues report, not a complete hardware diagnosis or a repair service. In particular, it cannot make a failing battery or other hardware healthy merely by reporting its status.
Free system-drive space with Storage Sense
Storage Sense manages selected files on the system drive. In Windows 11, open Settings > System > Storage, enable Storage Sense, then inspect its schedule and cleanup selections before relying on automatic cleanup. Microsoft’s instructions are in Manage drive space with Storage Sense.
With default settings, Storage Sense may run when the device is low on space and remove unnecessary temporary files. Recycle Bin contents may be removed after a period. Downloads and cloud files are left alone unless you configure those locations for cleanup, so review each selection carefully before changing it.
For other cleanup options, Microsoft also explains how to free up space for Windows updates. Storage Sense and Disk Cleanup can help make room, but deleting files is not a general diagnosis for slow performance.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.PC Health Check is a separate Windows 11 overview
Microsoft’s PC Health Check app guidance covers Windows 11. It can show Windows update status, startup time, storage use, device specifications, and battery capacity information where the device supports it. It is an overview, not a malware scanner or a complete explanation of every slowdown.
| Tool | Main purpose | What it covers | Important limit |
|---|---|---|---|
| Microsoft Defender Antivirus | Threat scanning and antivirus protection | Quick scans and scans of selected files or folders | Turns off automatically when another antivirus app is installed and turned on. |
| Firewall & network protection | Filter network traffic | Domain, private, and public network profiles | For an app access problem, allow the app rather than turning off the firewall. |
| Device performance & health | Surface selected device-health issues | Storage, battery strain where applicable, app/software issues or updates, and Windows Time service | Not a complete hardware diagnosis; an organization may hide the page. |
| Storage Sense | Free selected system-drive space | Temporary files and configured cleanup targets | Downloads and cloud files are excluded by default; review selections. |
| PC Health Check (Windows 11) | Provide a device and update overview | Update status, startup, storage, specifications, and supported battery information | Battery details depend on device support; not a malware scan or full performance diagnosis. |
When cleanup does not solve a performance problem
Recurring errors, slow startup, declining battery life, low storage, or persistently high CPU, memory, or disk use can point to issues that a scan or cleanup will not fix. Microsoft’s guidance on how to know it’s time for a new PC describes signs of aging or trouble; its home computer security guidance and update-space guidance offer related next steps.
- Find a persistent resource bottleneck: open Task Manager and check whether CPU, memory, or disk use remains high, and which process is using it.
- Check startup programs: review what launches when Windows starts and disable only items you recognize and do not need at startup.
- Install available Windows updates: use Windows Update and resolve any update issue rather than assuming a cleanup tool will do it.
- Back up important files: make a separate backup before troubleshooting further; cleanup tools are not backups.
- Escalate persistent hardware symptoms: if battery decline, recurring failures, or other physical symptoms continue, seek appropriate repair or upgrade advice.
Windows 10 support has ended
Microsoft ended Windows 10 support on October 14, 2025. That means free software updates through Windows Update, technical assistance, and security fixes ended; it does not mean Windows 10 stopped running. The cited Windows feature pages cover Windows 10 and Windows 11 in varying combinations, while PC Health Check guidance here is for Windows 11. For a Windows 10 PC still in use, do not mistake the presence of built-in tools for continued security fixes from Microsoft.
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