Why is my Windows PC so slow, and how to fix it
Find out why your Windows PC runs slow, then fix it: check startup apps, storage, malware and your drive type before assuming you need new hardware.
A slow Windows PC is almost always slow for a reason, and the fix is usually free. Microsoft’s own list of common causes is short: not enough storage space, too many apps launching and running in the background, software that is out of date, and hardware that no longer keeps up with what you ask of it. This guide walks through those causes in a sensible order so you diagnose the real problem first, then apply the matching fix instead of guessing.
Start with the cheap checks
Before you change any settings, restart the PC. Microsoft specifically recommends restarting rather than only shutting down or hibernating, because a restart clears memory and ends lingering processes that a shutdown may leave behind. While you are at it, close apps you are not using and trim the number of open browser tabs. These are cheap diagnostics: if the machine feels fine after a restart with fewer things open, you have learned that the problem is load, not failing hardware.
If the slowdown comes back, keep going. The rest of this guide is about finding which of Microsoft’s four causes is yours.
See what is actually using the machine
Open Task Manager with Ctrl+Shift+Esc (you can also right-click the Start button and choose it). The Processes tab lists everything running, and you can click the column headers to sort by CPU, Memory, or Disk. Sorting by Disk is often the most revealing on an older machine.
Brief spikes to 100% disk usage are normal. A disk that sits pinned near 100% while the PC crawls is the warning sign: the drive cannot keep up with what is being asked of it. Commonly cited culprits include Windows Search indexing, Windows Update running, an antivirus scan, low RAM forcing the system to page to disk, and outdated drivers or malware. Because the Processes tab names the process responsible, you can usually see which of these it is rather than guessing.
Check whether your drive is an SSD or a hard disk
This one detail explains a lot of slow PCs. In Task Manager, open the Performance tab; each disk shows a Type, listed as SSD or HDD (newer builds also show NVMe or SATA). Alternatively, open the tool called Defragment and Optimize Drives and read the Media type column, which says either Solid state drive or Hard disk drive.
If your system drive is a mechanical hard disk, it is very often the real bottleneck, and no amount of software tweaking will make it behave like a modern solid-state drive. It is also worth knowing that the Optimize Drives tool treats the two differently: hard disks are defragmented, while SSDs are sent a TRIM/optimize command instead. Windows schedules this automatically, so manually defragmenting an SSD is unnecessary.
Trim what launches at startup
Too many programs starting with Windows is one of Microsoft’s named causes of slowness. In Task Manager, open the Startup apps section. It lists every app set to launch when you sign in and shows each one’s Startup impact. To stop one from launching automatically, right-click it and choose Disable. That stops the automatic launch at sign-in without uninstalling the app. You can manage the same list outside Task Manager under Settings > Apps > Startup, where each app has an On/Off toggle.
It helps to know what the impact ratings actually mean, because they only measure resource use at sign-in.
| Rating | What it means |
|---|---|
| None | The app is disabled |
| Not measured | No data available; the app is enabled |
| Low | CPU under 300 ms and disk under 292 KB at startup |
| Medium | CPU under 1 second but over 300 ms, or disk under 3 MB but over 292 KB |
| High | CPU over 1 second, or disk over 3 MB |
A High rating does not mean an app is unwanted or unsafe. A backup client, a security component, or a hardware utility can legitimately be High. And disabling a startup entry only stops the launch at sign-in; it does not uninstall the app, and it does not necessarily stop that app’s separately registered Windows services or scheduled tasks. Disable what you recognize and do not need at login, and leave the rest alone.
Stop background apps and free up storage
Some apps keep working in the background even when you are not using them. On Windows 11 you can stop a specific app: go to Settings > Apps > Installed apps, open the app’s More options menu, choose Advanced options, and set its background app permission to Never. Older Windows 10 builds instead have a single Background apps page under Settings > Privacy.
Low free space is another of Microsoft’s named causes; it slows performance and can even block Windows updates. There is no official Microsoft free-space percentage, but widely cited guidance is to keep roughly 15% of a hard disk free and a comfortable margin on an SSD. The version-safe takeaway is simply that a nearly full drive drags, so give it room.
To reclaim space, open Settings > System > Storage. Storage Sense lives here; it is off by default, but when turned on it automatically frees space by clearing temporary files and the Recycle Bin, and it can be set to delete Recycle Bin items and unopened Downloads after a chosen number of days and to make unused cloud files online-only. The same Storage page has a Temporary files entry you can clear now, and the older Disk Cleanup tool is still present if you search for it from Start. Note that Storage Sense manages the system drive; other drives need separate attention.
Scan for malware
Malware can quietly consume CPU and disk and leave a PC feeling sluggish, so Microsoft recommends a scan as an early step when a machine slows down. Go to Settings > Privacy & security > Windows Security > Virus & threat protection and run a Quick scan, which checks the locations threats most often hide.
If you want to dig deeper, Scan options offers four types: Quick scan, Full scan (every file and running program), Custom scan (folders or drives you choose), and Microsoft Defender Offline scan, which restarts the PC and scans before Windows loads to catch rootkits and persistent malware that hide during normal operation. Before running an offline scan or any deep cleanup, it is sensible to back up your files first. Keep in mind that not every slowdown is malware; an aging PC or a newly installed, resource-heavy program is a common non-malware cause.
Update and tune Windows itself
Out-of-date software is the last of Microsoft’s four causes. Check for updates at Settings > Windows Update > Check for updates. Beyond updates, a few built-in settings can help an older machine feel more responsive:
- Visual effects: search for “Adjust the appearance and performance of Windows,” open the Visual Effects tab, and choose Adjust for best performance. This trades animations and shadows for speed.
- Power mode: on a desktop or a plugged-in laptop, go to Settings > System > Power & battery > Power mode and select Best performance.
Ignore the “PC cleaner” and registry tools
When a PC is slow, ads for registry cleaners and one-click optimizers appear everywhere. Skip them. Microsoft’s official support policy states that it does not support the use of third-party registry cleaning utilities and is not responsible for problems they cause. Editing the registry incorrectly can create serious problems, and modern Windows does not need registry cleaning for performance. The real fixes are the ones above; the download promising to make your PC “like new” is at best a placebo.
When it is the hardware, not the software
Sometimes the honest answer is that the machine has aged out. If Task Manager keeps showing memory maxed out, more RAM may be the fix; here is how to tell if your PC needs more RAM. If the system drive is a mechanical hard disk, moving to an SSD is usually the single biggest improvement you can make.
Two dates matter for a 2026 machine. Windows 11’s minimum requirements are a supported 64-bit processor of 1 GHz or faster with two or more cores, 4 GB of RAM, 64 GB of storage, UEFI with Secure Boot, and TPM 2.0. A PC that cannot meet these, especially TPM 2.0 and the supported-processor list, is a case where an upgrade, not tweaking, is the real answer. And Windows 10 reached end of support on October 14, 2025; since then it no longer receives security updates, bug fixes, or technical support, though consumers can enroll in a paid, limited Extended Security Updates program for extra coverage.
Where to go from here
Work through this in order and the cause usually reveals itself: restart and close what you are not using, open Task Manager to see what is consuming CPU and disk, check whether your drive is an SSD or a hard disk, trim startup and background apps, free up storage, scan for malware, then update and tune Windows. If every one of those checks out and the machine still struggles, you have your answer, and it is a hardware conversation rather than a settings one. Either way, you fixed the real problem instead of paying for a cleaner that does not.