PC Running Slow After Update? Here’s Why (And How to Fix It in 2026)

You know the feeling. It’s the digital equivalent of waking up on the wrong side of the bed. You finished work yesterday, saw that little orange dot on your power button, and thought, “I’ll just let it update while I sleep. It’ll run better tomorrow.”

But you wake up, wiggle the mouse, and… nothing. Or maybe not nothing, but everything is just sticky. Chrome takes ten seconds to open. Your mouse cursor is stuttering across the screen. You click the Start menu, and it thinks about it for a solid five seconds before popping up.

If your PC running slow after update is your current reality, take a deep breath. You haven’t broken your computer, and you (probably) don’t need to go out and buy a new one.

I’ve been fixing computers for over a decade, and I can tell you with 100% certainty: post-update sluggishness is the most common complaint I get. Whether you’re on the latest build of Windows 11 (or the newer iterations rolling out in 2026) or you’re holding onto Windows 10, updates are messy. They move things around, reset settings you forgot you changed, and sometimes, they just don’t play nice with your hardware.

In this guide, I’m going to walk you through exactly how to troubleshoot a computer lagging after update, starting with the easy stuff and moving to the “big guns” if necessary.

The “Wait and See” Approach (Don’t Skip This)

Before you start tearing your hair out or diving into the registry, we need to talk about the “settling in” period.

What most people don’t realize is that when Windows finishes installing an update, the progress bar hitting 100% doesn’t mean it’s actually done.

In the background, your operating system is doing a massive amount of housekeeping. It is:

• Re-indexing your files: So that Windows Search works (which causes high disk usage).
• Scanning for malware: The built-in Defender often does a full sweep after major system changes.
• Optimizing .NET framework: Basically, recompiling code so apps launch faster later, but slower now.

If you have high disk usage after update, or your fans are spinning like a jet engine, leave the computer on and idle for 1–2 hours.

I can’t tell you how many times a client called me in a panic, I told them to go grab lunch, and by the time they came back, the PC had sorted itself out. If it’s still sluggish after a few hours, then we have a real problem.

Step 1: Check for “Zombie” Processes (Task Manager)

If patience didn’t work, we need to find out what is eating your resources.

Sometimes, a windows update stuck optimizing in the background can hog 99% of your CPU. Here is how to catch it:

1. Press Ctrl + Shift + Esc to open Task Manager.
2. Click “More details” at the bottom if it looks empty.
3. Click the CPU column header to sort by usage.

What to look for: If you see “Windows Modules Installer Worker” or “Antimalware Service Executable” taking up 40-50% of your CPU, the update is still trying to finish something.

However, if you see high memory usage or disk usage from random apps, the update might have reset your startup preferences.

The “Disable Startup Programs” Trick

Updates are notorious for re-enabling apps you previously told to stay quiet.

1. In Task Manager, click the Startup apps tab.
2. Look for “High” impact apps.
3. Right-click and Disable anything you don’t need the second the computer turns on (like Steam, Spotify, or Cortana).

This is often the quickest way to fix a slow boot after update.

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Step 2: The Graphics Driver Conflict (The FPS Killer)

If you are a gamer or you do video editing, and you notice your update caused fps drops, this section is for you.

Here is a scenario I see constantly: Windows Update decides it knows better than NVIDIA or AMD. It sees your specialized, high-performance graphics driver and says, “Let me replace that with a generic Microsoft Basic Display Adapter driver.”

Suddenly, your games run like a slideshow.

How to fix it:

1. Right-click the Start button and select Device Manager.
2. Open Display adapters.
3. If you see “Microsoft Basic Display Adapter,” Windows nuked your driver.
4. Even if you see “NVIDIA GeForce…” or “AMD Radeon…”, it might be an outdated version pushed by Microsoft.

The Solution: Go directly to the manufacturer’s website (NVIDIA, AMD, or Intel). Download the latest driver manually and install it. Update graphics driver after windows update is my number one rule for gamers. Do not rely on Windows to keep your GPU current.

Step 3: Clean Up the “Old” Windows

When a major update installs (like the annual feature updates we see in late 2025/2026), Windows plays it safe. It keeps a copy of your entire previous operating system, just in case the new one fails.

This is stored in a folder called Windows.old. I’ve seen this folder take up 20GB to 50GB of space. If you are running on an SSD, specifically a smaller one (256GB or 512GB), filling it to near capacity will absolutely tank your SSD performance after update.

SSDs need breathing room to work fast.

How to perform a Windows Update cleanup:

1. Open the Start menu and type Disk Cleanup. Run it as Administrator.
2. Select your C: drive.
3. Crucial Step: Click the button that says Clean up system files. It will scan again.
4. Look for “Previous Windows installation(s)” and “Windows Update Cleanup.”
5. Check those boxes and hit OK.

Warning: Only do this if you are sure you don’t want to “undo” the update immediately. Once you delete these files, you can’t roll back easily.

Step 4: Repair Corrupted System Files

Sometimes the update process glitches. A file gets copied wrong, or a power fluctuation happens during the install. Now, Windows is trying to run on corrupted code.

We can fix this using two built-in tools. You don’t need to be a hacker to do this; you just need to type a few commands.

1. Right-click the Start button and select Terminal (Admin) or Command Prompt (Admin).
2. Type this command and hit Enter: sfc /scannow

This stands for System File Checker. It will look for broken Windows files and replace them with fresh ones. If it says “Windows Resource Protection found corrupt files and successfully repaired them,” restart your computer. You might be fixed right there.

If that doesn’t work, try the deeper cleaning command: DISM /Online /Cleanup-Image /RestoreHealth

Think of DISM as the tool that fixes the tool (SFC) that fixes Windows.

Step 5: The “Nuclear” Option (Uninstall or Rollback)

If you have tried everything above—drivers are updated, startup apps are disabled, disk is clean—and you are still facing a windows 10 update slow performance or Windows 11 lag, the update itself might be buggy.

In the tech world, we call this a “borked” update. It happens.

How to uninstall latest update windows:

1. Go to Settings > Windows Update > Update History.
2. Scroll down to Uninstall Updates.
3. Look at the dates. Find the one that installed the day your problems started.
4. Click Uninstall.

The Rollback Option: If it was a major version change (like 23H2 to 24H2), you usually have a 10-day window to “Go Back.”

1. Go to Settings > System > Recovery.
2. Look for the “Go Back” button.
3. Follow the prompts.

This is your escape hatch. If rollback windows update solves the problem, pause your updates for 2–3 weeks. Usually, Microsoft releases a “hotfix” within a few weeks to patch whatever caused the slowdown.

Common Mistakes: What NOT to Do

When your PC is lagging, desperation sets in. I’ve seen clients do some damage trying to fix things quickly. Here is what you should avoid:

• Don’t download “PC Booster” software: In 2026, these are almost all “snake oil.” They essentially just clear your cache (which you can do yourself) and serve you ads. They often use more background resources, making the problem worse.
• Don’t defrag your SSD: If you have a Solid State Drive (which almost all modern PCs do), do not run a traditional “defrag.” Windows handles SSD optimization (TRIM) automatically. Forcing a defrag just reduces the lifespan of the drive.
• Don’t immediately reset the PC: A full factory reset is a massive hassle. You lose apps and settings. Treat that as the absolute last resort.

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Real-World Scenario: The “KB” Update Disaster

Let me share a quick example from last month. A graphic designer friend of mine called me. Her $3,000 workstation was crawling. Windows search indexing slow, folders taking forever to load. She was ready to buy a new drive.

We looked at her update history. A specific security update (let’s call it KB505xxxx) had installed that morning. A quick Google search of that KB number showed hundreds of people on Reddit complaining about the exact same thing.

We uninstalled just that specific update, paused updates for 7 days, and her PC was instantly back to normal. Two weeks later, she unpaused, the update re-installed (patched by Microsoft), and everything was fine.

Sometimes, it’s not you. It’s the code.

FAQs: Quick Answers for Slow PCs

Conclusion: Don’t Panic, Just Troubleshoot

Having a PC running slow after update is incredibly frustrating, especially when technology is supposed to make our lives faster, not slower. But remember: software is complex. With millions of different hardware combinations out there, updates are bound to trip over their own shoelaces occasionally.

Start with patience. Let the background tasks finish. Then, check your drivers (especially graphics), clear out the startup junk, and if all else fails, don’t be afraid to hit that uninstall button on the update.

Your computer is a tool, and you are the master of it. Don’t let a bad line of code ruin your workflow.