Windows 11 Running Slow? 15 Fixes That Actually Work

Written by the Softkeyworld technical team · Updated October 2026

"My PC has gone slow" is one of the vaguest complaints in IT support. It can mean a 3-minute boot, a stuttering cursor, Explorer taking seconds to open a folder, or a fan running flat out while nothing seems to be happening. Each has a different cause, so this guide is in diagnostic order: measure first, then fix the cheapest and most likely problems before moving on to repairs and reinstalls. Every step uses tools built into Windows 11. You do not need to download a "PC optimiser", and we recommend that you don't.

Before you start: identify the type of slowness

Match your symptom to its most likely cause, then jump to the relevant fix.

Symptom	Most likely cause	Start with fix
Slow boot and sign-in	Startup apps, HDD, pending updates	3, 6, 7
Everything sluggish, disk at 100%	Failing or full drive, indexing, sync	5, 6, 9
Fans loud, CPU high at idle	Runaway process, malware, overheating	2, 8, 14
Slow only on battery	Power mode or energy saver	4
Slow after a recent update	Driver or update regression	7, 12
Memory always above 90%	Too little RAM for the workload	2, 13, 14

Quick wins (5 minutes)

1. Do a real restart

With Fast Startup enabled, Shut down saves the kernel session to disk rather than ending it, so a PC that is "turned off every night" may not have truly restarted in weeks. Open Task Manager, go to Performance > CPU and check Up time. If it shows days or weeks, choose Start > Power > Restart. This clears leaked memory, stuck drivers and half-installed updates, and it fixes more slowness than it should.

2. Find the process that is actually responsible

Press Ctrl + Shift + Esc, open Processes, and click the CPU, Memory and Disk column headers in turn to sort by each. A single process that stays near the top, such as a browser with 60 tabs, a sync client, or an antivirus scan, is your answer. For more detail, run resmon to open Resource Monitor. On the Disk tab you can see which file each process is reading or writing. Common culprits are Antimalware Service Executable during a scheduled scan, Windows Search indexing, and Microsoft OneDrive catching up on a large library. These are usually temporary.

3. Trim startup apps

Go to Settings > Apps > Startup, or the Startup apps page in Task Manager, which shows a Startup impact rating for each entry. Turn off anything you do not need the moment you sign in, such as game launchers, updaters, chat apps and printer utilities. Keep your security software, audio and touchpad drivers. Disabling an entry does not uninstall the app; it simply stops it launching automatically.

4. Check the power mode

Open Settings > System > Power & battery > Power mode. Laptops often default to Balanced or a vendor eco profile and throttle hard on battery. On mains power, set Best performance and compare. If Energy saver is turned on, it also reduces background activity and screen brightness. Some manufacturers add their own performance profiles (often a function-key shortcut or a preinstalled control app), and these can override Windows' setting.

5. Free up disk space

When the system drive is nearly full, Windows has little room for the page file, updates and temporary files, and everything slows down. Go to Settings > System > Storage, open Temporary files and remove what you do not need. Windows Update Cleanup and Delivery Optimization Files are usually safe to delete. Check the Downloads box carefully before ticking it. Turn on Storage Sense so this happens automatically. As a working rule, we try to keep at least 15–20% of the system drive free.

Hardware and update checks

6. Check what kind of drive you have, and its health

Windows 11 on a spinning hard drive is slow, whatever else you do. Open PowerShell and run Get-PhysicalDisk | Select FriendlyName, MediaType, HealthStatus. If the system disk shows HDD, moving to an SSD is the single biggest upgrade you can make. On NVMe drives, Settings > System > Storage > Advanced storage settings > Disks & volumes > Properties shows drive health, including estimated remaining life and temperature. A health status of Warning or Unhealthy means you should back up now, before you try anything else.

7. Update Windows and drivers, or roll back a bad update

Go to Settings > Windows Update and install everything, then check Advanced options > Optional updates for driver updates. For chipset, storage and graphics drivers, the PC or motherboard manufacturer's support page is often more current. If the slowdown began straight after an update, go to Update history > Uninstall updates and remove the most recent cumulative update to test. If updates themselves are stuck or failing, our guide to fixing a stuck Windows 11 update covers that separately.

8. Scan for malware properly

Cryptominers and adware are designed to use spare CPU quietly. Open Windows Security > Virus & threat protection > Scan options and run a Full scan. If you suspect something is hiding, run a Microsoft Defender Offline scan, which reboots and scans before Windows loads. Be wary of "free" activators and cracked software. In our experience, they are one of the most common sources of hidden miners on slow machines.

Settings that quietly cost performance

9. Tame indexing, sync and background apps

In Settings > Privacy & security > Searching Windows, the Enhanced option indexes your whole PC. Classic indexes only libraries and the desktop, which is enough for most people and uses much less disk activity. For OneDrive, pausing sync for a couple of hours while a large first sync completes can make the machine usable again. For individual Store apps, go to Settings > Apps > Installed apps, click the three dots, choose Advanced options and set Background app permissions to Never where it makes sense.

10. Reduce visual effects on low-end hardware

Press Win + R, run SystemPropertiesPerformance and choose Adjust for best performance. Then re-tick Smooth edges of screen fonts and Show thumbnails instead of icons, because text looks poor without them. You can also turn off Settings > Accessibility > Visual effects > Animation effects and Transparency effects. On a modern GPU the gain is negligible, but on older laptops with integrated graphics, menus feel noticeably faster.

11. Remove duplicate security tools and "optimisers"

Two real-time antivirus products scanning the same files will slow each other down. If you have a third-party suite, Microsoft Defender steps back automatically, but leftover trial suites and "registry cleaners" often keep running their own services. Go to Settings > Apps > Installed apps, sort by install date and remove anything you do not recognise or no longer use, particularly preinstalled trials.

Deeper repairs

12. Repair Windows system files with DISM and SFC

If slowness comes with crashes, broken Settings pages or apps that refuse to open, repair the component store and then the system files. Open Terminal (Admin) and run, in order:

1. DISM /Online /Cleanup-Image /RestoreHealth repairs the Windows image using Windows Update as the source. It can sit at 62.3% for a while, which is normal.
2. sfc /scannow checks protected system files against that repaired store.
3. Restart, even if SFC reports that it found nothing.

Microsoft documents the DISM options in its guide to repairing a Windows image. If DISM fails with source errors, a clean in-place repair (fix 15) is the next step.

13. Make sure the page file has not been disabled

Old "tweak guides" still recommend turning off virtual memory. On a PC with 8 GB of RAM, that leads to apps closing unexpectedly and severe slowdowns under load. Open SystemPropertiesPerformance, go to Advanced > Virtual memory > Change and make sure Automatically manage paging file size for all drives is ticked. If Task Manager shows memory above 90% during normal work, the real fix is more RAM. In our experience 16 GB is comfortable for typical office use, even though Windows 11 installs with 4 GB.

14. Rule out heat and faulty memory

A laptop that is fast for five minutes and then slows down is usually thermal throttling. Dust-clogged vents and dried thermal paste are common causes on machines that are three or more years old. Watch the CPU speed in Task Manager > Performance > CPU under load. If it drops well below the base clock, cleaning the cooling system is the fix. For random freezes, run mdsched.exe (Windows Memory Diagnostic) to test the RAM on the next restart.

15. Reinstall Windows while keeping your files, or start clean

When nothing else works, a repair reinstall replaces every Windows file while keeping your apps and data. On current Windows 11 builds, look for Settings > System > Recovery > Fix problems using Windows Update, which downloads and reinstalls your current version. The alternative is Reset this PC with Keep my files, which removes installed apps. Before either option, confirm you can access your BitLocker recovery key, because firmware or boot changes can prompt for it. Our guide to finding your BitLocker recovery key shows where to look. For a completely fresh start, prepare install media using our Windows 11 bootable USB guide. Your digital licence reactivates automatically on the same hardware.

What does not make Windows 11 faster

• Registry cleaners. They remove harmless leftover keys and occasionally break things. Microsoft does not support their use.
• "Debloat" scripts from unknown sources. Some remove components that Windows Update later needs, which leads to failed updates.
• Changing edition. Pro, Pro for Workstations and Enterprise run at the same speed on the same hardware. See our edition comparison for what does differ.
• Modified "lite" ISOs. They are unsupported, often out of date and potentially compromised. Use official Microsoft media only.
• Defragmenting an SSD manually. Windows already sends TRIM to SSDs on a schedule through Defragment and Optimise Drives; leave it set to automatic.

Microsoft's own tips to improve PC performance cover the same built-in tools used above, which is a good sign that you do not need third-party software for any of this.

Frequently asked questions

Why is Windows 11 so slow after an update?

For the first hour or so after a feature update, Windows re-indexes files, optimises apps and finishes background tasks. If it is still slow a day later, check for driver updates, or uninstall the latest cumulative update to test whether it is the cause.

How much RAM does Windows 11 really need?

The minimum is 4 GB, but in practice 8 GB is the floor for light use and 16 GB is comfortable for office multitasking with a modern browser.

Why is my disk at 100% in Task Manager?

On hard drives this is common during updates, indexing or antivirus scans. If it persists on an SSD, check drive health and use Resource Monitor to see which process is reading or writing.

Does an unactivated Windows 11 run slower?

No. Activation status does not affect performance; it restricts personalisation and shows a watermark. However, unofficial activators can install malware that does slow the PC down.

Will resetting Windows 11 make it faster?

Usually, yes, if the cause was software: years of accumulated apps, services and drivers. It will not help a failing drive, overheating or insufficient RAM.

Is it safe to disable all startup apps?

Mostly, but leave your security software, audio and input device utilities enabled. Anything you disable can be switched back on from the same page.

Our recommendation

Work through the fixes in order and stop when the problem is gone; most PCs are back to normal by step 6. If you end up doing a clean reinstall on a machine that never had a valid licence, or you are building a new SSD-based system, a genuine Windows 11 Pro licence key activates cleanly and receives every security update. Our support team can help with activation at support@softkeyworld.com.

Get a Genuine Windows 11 Pro Key

Related reading

Resource	Why read it
Windows 11 update stuck fix	When updates themselves fail or hang
Find your BitLocker recovery key	Essential before any reset or repair
Create a Windows 11 bootable USB	Official media for a clean reinstall