How to Fix a Slow PC After a Windows Update

Common causes

Windows Search re-indexing your files, email, and apps after the update, which uses disk and CPU until it catches up.
Other post-update background work, such as .NET optimization, Microsoft Store app updates, OneDrive sync, and Defender scanning newly changed files.
A pending restart that leaves the update partly installed until Windows can replace files that were in use.
A graphics or chipset driver replaced by a generic or less suitable version during the update.
Startup apps that were re-enabled or newly added, including apps that updated themselves at the same time.
Low free space on the system drive, made worse by the Windows.old folder a feature update keeps for rollback.
A power mode set to battery saving or efficiency, which limits performance even when the PC is plugged in.
A faulty update, corrupted system files, or malware that happened to arrive around the same time as the update.

Step-by-step fixes

Step 1

Restart and finish any pending updates

Many updates aren't finished until you restart, and some need more than one restart. Open Settings > Windows Update in Windows 11 (Settings > Update & Security > Windows Update in Windows 10). If you see Restart now or a restart required message, save your work and restart. Then select Check for updates and install anything else offered, because follow-up cumulative updates often fix problems introduced by earlier ones. Use Start > Power > Restart rather than Shut down, since Fast Startup means a shutdown doesn't fully reset Windows. Leave the PC plugged in and idle for a while after restarting so installation work can complete. Success is Windows Update showing that you're up to date with no restart pending.

Step 2

Let indexing and background optimization finish

After a major update, Windows rebuilds its search index and optimizes apps in the background, which can make the PC feel sluggish for hours. Press Ctrl + Shift + Esc to open Task Manager and sort the Processes list by CPU or Disk. Names such as Microsoft Windows Search Indexer, Antimalware Service Executable, .NET Runtime Optimization Service, and Windows Modules Installer Worker are normal after updates and settle down on their own. To check indexing in Windows 11, open Settings > Privacy & security > Searching Windows (Windows 10: Settings > Search > Searching Windows). If indexing never finishes, switch Find my files from Enhanced to Classic, or open Advanced indexing options > Advanced and select Rebuild. Success is CPU and disk use dropping to low levels while the PC is idle.

Step 3

Disable unnecessary startup apps

Updates sometimes re-enable startup apps, and apps that updated at the same time may have added themselves. In Windows 11, open Task Manager (Ctrl + Shift + Esc) and select Startup apps; in Windows 10, select the Startup tab. Sort by Startup impact and disable anything you don't need running all the time, such as game launchers, chat apps, updaters, and manufacturer utilities you never open. Right-click an entry and select Disable. This doesn't uninstall the app; it only stops it launching when you sign in. Keep your antivirus and your touchpad, audio, and graphics software enabled. You can also manage the list in Settings > Apps > Startup. Restart and compare. Success is a faster sign-in and fewer icons in the notification area.

Step 4

Check your power mode

A power setting can make a PC noticeably slower, especially a laptop. In Windows 11, go to Settings > System > Power & battery (called Power on some desktops) and set Power mode to Balanced or Best performance while plugged in. Also check that Energy saver or Battery saver isn't switched on. In Windows 10, select the battery icon on the taskbar and move the slider toward Best performance, or open Control Panel > Hardware and Sound > Power Options and choose Balanced or High performance. Many laptop makers also include their own performance modes in a preinstalled control app, so check that setting too. Success is quicker app launches when plugged in, without the fan running hard while the PC is idle.

Step 5

Update or roll back graphics and chipset drivers

Windows Update sometimes installs a generic or older driver that performs worse than the one your PC shipped with. Right-click Start, open Device Manager, expand Display adapters, right-click your graphics card, and select Properties > Driver. If the slowdown began right after the update and Roll Back Driver is available, use it. Otherwise, install the latest driver from NVIDIA, AMD, or Intel, or from your laptop or motherboard maker's support page, which also provides chipset drivers. In Windows 11, check Settings > Windows Update > Advanced options > Optional updates for driver updates as well (Windows 10: View optional updates). Restart after each change. If Device Manager shows Microsoft Basic Display Adapter, the proper graphics driver is missing. Success is smooth scrolling and video, with your actual graphics card named in Device Manager.

Step 6

Free up storage and turn on Storage Sense

Windows slows down when the system drive is nearly full. Open Settings > System > Storage in Windows 10 or 11 and select Temporary files. Select items such as Windows Update Cleanup, Delivery Optimization Files, and Temporary files, then select Remove files. Don't tick Downloads unless you've checked that folder first. After a feature update you'll also see Previous Windows installation(s); deleting it frees a lot of space but removes your option to go back to the earlier version, so leave it until you're sure the update is fine. Turn on Storage Sense on the same page to clean temporary files automatically in future. Success is a system drive that's no longer close to full, with comfortable free space for Windows to work with.

Step 7

Repair system files and check for malware

If Windows is still slow or apps crash, check for corrupted files. Right-click Start, open Terminal (Admin) or Windows PowerShell (Admin), and run DISM /Online /Cleanup-Image /RestoreHealth, then sfc /scannow. Let each command finish even if progress seems to pause, and restart afterward. SFC reports whether it found and repaired corrupt files. Next, rule out malware that arrived around the same time. Open Windows Security > Virus & threat protection > Scan options, run a Full scan, and consider a free second-opinion scan with a tool such as Malwarebytes. In Task Manager, watch for unfamiliar processes using heavy CPU or network while the PC is idle. Success is a clean SFC result, no malware detections, and normal resource use at idle.

Step 8

Uninstall the update or go back to the previous version

If the slowdown clearly started with one update and nothing else helped, remove it. Back up important files first. For a monthly update in Windows 11, open Settings > Windows Update > Update history > Uninstall updates and remove the most recent one (Windows 10: Settings > Update & Security > Windows Update > View update history > Uninstall updates). For a feature update, go to Settings > System > Recovery and select Go back (Windows 10: Settings > Update & Security > Recovery > Go back to the previous version of Windows). This is only available for 10 days after the upgrade, and only if Previous Windows installation(s) hasn't been deleted. Afterward, pause updates briefly from Windows Update so it doesn't reinstall straight away. Success is normal speed restored.

How to prevent it

Restart promptly when Windows asks, and leave the PC on and plugged in for a while after big updates so background work can finish.
Keep plenty of free space on the system drive and leave Storage Sense turned on.
Install graphics and chipset drivers from your hardware maker, and review optional driver updates before accepting them.
Keep your startup apps list short, and review it after each major update.
Back up regularly so you can roll back or reset without worrying about losing files.

Tools that can help

Almost every post-update slowdown can be fixed with the free Windows tools above. A malware scanner is only worth adding if the PC stays slow with unexplained activity after updates, drivers, and startup apps are sorted.

Best for cleanup

Malwarebytes

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What to do next if this fails

Move to the next fix instead of repeating the same step multiple times.
Check the related guides in this cluster before attempting a full reset.
If startup, update, and corruption symptoms overlap, widen the diagnosis instead of treating one error in isolation.

FAQ

How long does a PC stay slow after a Windows update?

After a monthly update, any slowdown usually clears after a restart or two. After a major feature update, background indexing and app optimization can keep the PC busy for several hours, and sometimes longer on slower drives. Leave it on, plugged in, and idle for a while to let that work finish. If it's still slow after a couple of days, the cause is more likely a driver, startup app, or faulty update.

Is it safe to uninstall a Windows update?

Yes. Uninstalling a recent quality update through Settings is a supported option and doesn't touch your files. The trade-off is security: monthly updates contain security fixes, so removing one leaves those holes open. Only uninstall an update when you're confident it caused the problem, pause updates briefly, and let it reinstall once Microsoft has released a fix. Back up important files before making changes.

Why is Antimalware Service Executable using so much CPU after an update?

That's Microsoft Defender scanning files that changed during the update, which is normal and usually settles on its own. If it stays high for days, make sure Defender's security intelligence is up to date, restart, and let one full scan complete. Don't disable Defender to fix it. If you've installed another antivirus, Defender should already have stepped aside automatically.

Should I delete the Windows.old folder to speed up my PC?

Deleting it frees disk space, which helps if your drive is nearly full, but it won't make an otherwise healthy PC faster. It also removes your ability to go back to the previous version of Windows. Wait until you're sure the update is working well. Windows removes it automatically after the rollback period, or you can delete it from Settings > System > Storage > Temporary files.

Can I stop Windows from installing updates that slow my PC?

You can pause updates for a few weeks from Settings > Windows Update, which gives Microsoft time to fix a problem update. Blocking updates permanently isn't a good idea, because it leaves your PC exposed to known security holes. A better approach is to keep updating, install drivers from your PC maker, and roll back a specific update only when it's clearly causing trouble.

Will resetting Windows fix slowness after an update?

Usually, but it's a last resort because it removes your installed apps. Try the steps above first, since most post-update slowdowns come from drivers, startup apps, storage, or background tasks. If you do reset, go to Settings > System > Recovery > Reset PC, choose Keep my files, back up anyway, and reinstall apps afterward. A reset won't fix a PC that's slow because of a failing drive.