How to Fix a Slow Computer in Windows 11

To fix a slow computer in Windows 11, restart it, install Windows updates, run a virus scan, free up disk space, and turn off startup apps you don’t need. If those don’t help, use Task Manager to find the app that is using your memory, processor or disk, then try the deeper fixes further down.

These steps cover Windows 11, including version 26H2 (the Windows 11 2026 Update), 25H2 and 24H2. Most also work in Windows 10 with slightly different menu names, covered near the end. They follow Microsoft’s tips to improve PC performance in Windows, which lists twelve built-in fixes. Microsoft also notes that older PCs with outdated hardware may not improve much, so an upgrade can be the long-term fix.

Before You Start

• Save your work. Several fixes restart the PC.
• Use an administrator account if you can. Uninstalling apps and running repair tools may ask for an administrator password.
• Skip third-party “cleaner” and “optimizer” apps. Every fix here uses tools already in Windows. Registry cleaners are not needed and can cause new problems.

Find Out What Is Slowing Your PC

A quick look at Task Manager tells you which fixes matter most.

1. Press Ctrl + Shift + Esc to open Task Manager. You can also right-click Start and select Task Manager. There are other ways to open Task Manager in Windows 11 as well.
2. Select Processes. You see each running app with its CPU, Memory and Disk use.
3. Select a column heading, such as Memory, to sort the list so the heaviest apps are at the top.
4. Select Performance and check CPU, Memory and Disk. A graph that stays near 100% shows where the bottleneck is.

Use what you find to pick a fix:

What Task Manager shows	What it usually means	Start with
One app uses most of the CPU	That app is busy or stuck	Close it, update it, or uninstall it
Memory In use is close to your total RAM	Too many apps or browser tabs open	Close apps, turn off startup apps
Disk stays at or near 100%	Updates, a scan, syncing, or a full drive	Let updates finish, free up space
Everything is low but the PC still lags	Settings, drivers or system files	Updates, power mode, repair tools

Quick Fixes to Try First

1. Restart your PC. Select Start > Power > Restart, then open only the apps you need. Restarting clears out programs and processes that pile up over time. Closing extra browser tabs helps too, since each tab uses memory.
2. Install updates. Go to Settings > Windows Update > Check for updates, and install anything listed. If it says You’re up to date, select Advanced options > Optional updates to check for driver updates. If an update fails, here’s how to fix failed updates in Windows 11.
3. Scan for malware. Go to Settings > Privacy & security > Windows Security > Virus & threat protection > Quick scan. For a deeper check, run a full or offline Windows Defender scan.
4. Free up space. Go to Settings > System > Storage. Select Temporary files, check the items you want to remove, and select Remove files. Read the list first: it can include your Downloads folder. After an upgrade, deleting Windows.old can free a lot of space.

5. Turn on Storage Sense. On the same Storage page, turn on Storage Sense, then select it to choose how often it runs and how long items stay in the Recycle Bin and Downloads before they are deleted. Select Run Storage Sense now to clean up right away. Microsoft says your drive is in a low disk state when the bar on the Storage page turns red.

You can also search for Disk Cleanup, open it, and pick the drive to clean. Many slowdowns clear up after these steps, especially ones caused by pending updates, malware or a nearly full drive.

If the slowdown started after a crash or power cut, or files won’t open, run CHKDSK in Windows 11 to check the drive for file system errors.

If only Excel lags when you move between cells, fix the slow cursor in Excel.

Stop Apps From Slowing You Down

1. Uninstall unused apps. Go to Settings > Apps > Installed apps, select More options (…) next to the app, and select Uninstall. Trial software that came with a new PC is a common culprit. Uninstalling a program on Windows 11 covers more ways to remove programs.
2. Turn off startup apps. Press Ctrl + Shift + Esc, select Startup apps, right-click an app you don’t need at sign-in, and select Disable. The app stays installed and still opens when you start it yourself.

3. Check the Startup impact column and start with apps marked High. Keep your antivirus on. If you are unsure about an app, disable it, restart, and turn it back on if something stops working. Changing startup programs in Windows 11 covers the Settings method too.
4. Stop background apps. In Installed apps, select More options (…) > Advanced options. Under Background app permissions, set Let this app run in the background to Never. Not every app shows this option. To find out which apps are worth stopping, check what’s running in the background.
5. Turn off unneeded notifications. Go to Settings > System > Notifications and switch off apps you don’t need alerts from.

If OneDrive is uploading a large batch of files, it can slow an older PC for a while. Select the OneDrive icon on the taskbar to see its progress, and let it finish or pause syncing until you are done working.

Fine-Tune Windows Performance

• Reduce visual effects: search for Adjust the appearance and performance of Windows, open the Visual Effects tab, and choose Adjust for best performance, then select OK. Windows looks plainer, with fewer animations and shadows. To undo it, choose Let Windows choose what’s best for my computer.
• Change power mode: in Settings > System > Power & battery, set Power mode to Best performance. Expect more power use, faster laptop battery drain and possibly a warmer machine. Switch back to Balanced when you are on battery.
• Optimize drives: search for Defragment and Optimize Drives, select the drive, and select Optimize. Windows defragments hard drives and trims SSDs, and it runs this weekly by default (see Microsoft’s drive optimization guide). Don’t force a traditional defrag on an SSD.
• Check memory use: in Task Manager, open Performance > Memory. If In use is close to your total RAM, open Processes, sort by Memory, save your work, and close the heaviest app normally. Cached memory isn’t wasted, so you don’t need a RAM cleaner (Microsoft’s memory footprint guidance covers why). Avoid ending processes you don’t recognize, since some belong to Windows.

Microsoft also offers its own free Microsoft PC Manager app, which brings storage cleanup and startup app management into one place. It is optional; the steps above do the same jobs. If you already use Norton 360, its Startup Manager can delay or disable startup programs as well.

If only games feel slow, check that you have Game Mode turned on in Windows 11.

If Your PC Is Still Slow

• Repair system files: damaged Windows files can cause lag and freezes. Type cmd in the search box, right-click Command Prompt, and select Run as administrator. Type DISM.exe /Online /Cleanup-image /Restorehealth and press Enter, wait for it to finish, then type sfc /scannow and press Enter. Keep the window open until it reaches 100%. Microsoft’s System File Checker guide explains each message.
• Check for overheating: a hot processor slows itself down to cool off. A CPU temperature check in Windows 11 tells you if that’s happening.
• Undo a recent change: if the slowdown started after installing a driver or app, do a System Restore to roll back to a point before the problem. Your personal files are not affected.
• Reset Windows as a last resort: go to Settings > System > Recovery, and next to Reset this PC select Reset PC. Keep my files reinstalls Windows and keeps your personal files but removes your apps and settings. Remove everything also deletes your files. Back up first and have your BitLocker recovery key ready if the drive is encrypted. Microsoft’s reset your PC page explains each option.
• Consider hardware: if Task Manager shows memory or disk use near 100% during everyday tasks, the PC may need more RAM or a solid-state drive (SSD). On many older PCs, moving from a hard drive to an SSD is the biggest upgrade. Check your PC maker’s support site to see what your model supports.

How to Tell if It Worked

Restart the PC and time how long it takes to reach a usable desktop, then open the apps you use most. Open Task Manager again: Memory and Disk should no longer sit near 100% when you are doing light work. If one fix made no difference, you can undo it. Turn a startup app back on with Enable, switch the power mode back to Balanced, or choose Let Windows choose what’s best for my computer for visual effects.

If the PC is still slow after every fix, back up your files and consider a clean reinstall of Windows 11.

Still on Windows 10?

Windows 10 support ended on October 14, 2025, so it no longer gets regular security updates, and upgrading to Windows 11 (if your PC qualifies) is the long-term fix. The same checks work with older menu names: Windows Update is under Settings > Update & Security, unused apps are under Apps > Apps & features, and Task Manager has a Startup tab instead of Startup apps. If Task Manager opens in a small window, select More details first.

Frequently Asked Questions