Windows 11 Running Slow After an Update? How to Fix It

The machine was fine on Monday. Windows updated overnight. Now the Start menu takes four seconds to open and Chrome feels like it’s running underwater.

Most guides respond to this with twenty tips in no particular order, which means you try all twenty and never learn which one mattered. This one starts with the diagnosis, because the fix depends entirely on what’s actually saturated.

Before anything: wait 48 hours

This isn’t a stalling tactic. After a feature update Windows genuinely does a large amount of work, and it’s work you want it to finish:

• Windows Search rebuilds its index of every file on the drive from scratch.
• .NET Runtime Optimization recompiles installed applications for the new build.
• Windows Update downloads and installs drivers for hardware it re-detected.
• Superfetch and prefetch caches are discarded and relearned from how you use the machine.

On an SSD this is done in a few hours. On a mechanical hard drive it can take most of a day. Leave the PC on and awake during that time. If you troubleshoot in this window, you’re measuring a system that is supposed to be busy, and you’ll reach the wrong conclusion.

Diagnose in 30 seconds

Press Ctrl + Shift + Esc to open Task Manager, click More details, then Performance. Use the machine until it feels slow and watch which graph is pinned.

What’s at 100%	Most likely cause	Go to
Disk	Search indexing, a failing or mechanical drive, or SysMain	Fix 1 and Fix 5
CPU	.NET optimisation, antivirus rescan, or a runaway startup app	Fix 2 and Fix 3
Memory	Too many startup apps, or a driver leaking memory	Fix 3 and Fix 4
Nothing, but it’s still slow	Graphics driver reverted to a generic version	Fix 4

Sort the Processes tab by the saturated column too. The name at the top is usually the answer.

Fix 1: Check whether Search is still indexing

Go to Settings → Privacy & security → Searching Windows. At the top it tells you how many items are indexed and whether indexing is still running.

If it’s in progress, that’s your answer and the fix is patience. If it says indexing is complete but SearchIndexer.exe is still hammering the disk days later, the index is corrupt. On that same page, scroll to Advanced indexing options → Advanced → Rebuild. It’ll be slow for a few hours and then normal.

Fix 2: Let .NET finish, or nudge it along

If Task Manager shows Microsoft .NET Framework NGEN or mscorsvw.exe eating the CPU, it’s recompiling your applications for the new Windows build. It runs at low priority and normally finishes on its own within a day.

To speed it up, open Command Prompt as administrator and run:

cd C:\Windows\Microsoft.NET\Framework64\v4.0.30319
ngen.exe executequeueditems

That tells it to do all the queued work now instead of trickling it out in the background. The machine will be busy for a while, then done with it for good.

Fix 3: Audit what starts with Windows

Feature updates re-enable startup entries that you’d previously turned off, and applications reinstalled during the update add themselves back.

1. In Task Manager, open the Startup apps tab.
2. Sort by Startup impact.
3. Disable anything marked High that you don’t need running from the moment you log in.

Usual suspects: cloud storage clients, game launchers, chat apps, printer utilities, and manufacturer “assistant” software. Disabling a startup entry doesn’t uninstall anything, and you can still open the app normally.

Leave your antivirus and anything from your GPU manufacturer alone.

Fix 4: Reinstall your graphics and chipset drivers

This is the one that catches people out, because nothing looks broken. Windows Update sometimes swaps a manufacturer driver for its own generic version. Everything still works. It’s just slower, and there’s no error to tell you.

The symptom is scrolling and window animations feeling sticky while Task Manager shows nothing unusual.

• Download the current driver from NVIDIA, AMD or Intel directly, not from Windows Update.
• On a laptop, get it from the laptop maker’s support page instead. Their builds handle power management for that specific chassis.
• Install the chipset driver too. It’s the one everyone skips and it governs how the CPU talks to storage and USB.

If the same update also left you with a blank screen at boot, that’s the more urgent version of this same problem. We covered the black screen case separately here.

Fix 5: Reclaim disk space and check the drive

A feature update keeps the previous installation in Windows.old so you can roll back. That’s often 20 to 30 GB, and a drive under about 10% free space slows down noticeably.

1. Open Settings → System → Storage → Cleanup recommendations.
2. Remove Previous Windows installation(s) and Windows Update Cleanup.

One caveat: deleting Windows.old removes your ability to roll back the update. Make sure everything works first.

While you’re there, check the drive’s health. Open Command Prompt as administrator and run chkdsk C: /scan. If it reports errors, or if Task Manager shows the disk at 100% active time while transferring almost no data, the drive itself is the bottleneck. On a mechanical hard drive that’s not a fault so much as a limit: each Windows release assumes faster storage than the last, and an SSD is the only real fix.

Fix 6: Turn off the visual extras

Worth doing on older or integrated-graphics machines. It won’t transform a genuinely overloaded PC, but it makes the interface feel noticeably snappier.

• Settings → Accessibility → Visual effects – turn off Transparency effects and Animation effects.
• Settings → System → Power – set the power mode to Best performance. On laptops this costs battery life, so decide accordingly.

What not to do

• Registry cleaners and “PC optimisers”. Windows doesn’t accumulate meaningful registry cruft, and these tools regularly delete entries that applications depend on. Every legitimate thing they do is available in built-in tools that show you what they’re changing.
• Disabling services from a list you found online. Turning off services you don’t understand produces problems that surface weeks later, with no obvious connection to what you did.
• Buying RAM before checking Task Manager. If memory isn’t near capacity, more RAM changes nothing. Confirm the bottleneck first.

If none of this helps

Two options remain, in order of effort.

Roll back the update. Available for ten days after a feature update, under Settings → System → Recovery → Go back. Treat it as a diagnosis rather than a cure: it confirms the update caused it, and the update will return. Use the time to get proper drivers installed.

Clean install. Slow but effective, and the honest answer for a machine that’s accumulated years of software. You’ll need your licence to hand. Check Settings → System → Activation first: if it says Windows is activated with a digital licence linked to your Microsoft account, it will reactivate on its own after the reinstall and you don’t need to buy anything. The full USB installation walkthrough is here.

If activation doesn’t come back, this guide covers the error codes, and a genuine Windows 11 Pro Retail key is $15. If your PC can’t meet Windows 11’s hardware requirements and you’re considering going back, Windows 10 Pro is also $15.

Frequently asked questions

The short version

Wait two days before concluding anything. Then open Task Manager and find out which resource is pinned, because that decides everything else. Disk usually means indexing or an ageing drive. CPU usually means .NET recompiling or a startup app. Nothing pinned but still sluggish usually means a generic graphics driver that Windows installed over yours.

Fix the one thing the diagnosis points at. Skip the twenty-tip checklist.