Why Your Windows PC Is Sluggish & How to Fix It (Extremely Detailed Guide)

A digital illustration showing the title “Fix Slow Windows PC – Step-by-Step Guide” with a laptop displaying the Windows logo and an hourglass on the screen, surrounded by icons representing slow performance, system alerts, and optimization.

Do you sometimes find your Windows PC running slowly, freezing, or acting laggy—especially when many windows are open or right after startup? This guide provides a thorough, step-by-step look at potential causes and practical solutions.

1. Unnecessary Apps or Background Processes

Often, the reason Windows slows down is because unnecessary apps or processes consume CPU or memory behind the scenes.

How to check:
① Press Ctrl + Shift + Esc to open Task Manager—or right-click the Taskbar and select “Task Manager“.

② Go to the “Processes” tab.

③ Sort by CPU or Memory usage and identify anything consuming too much.

④ If it’s non-essential, right-click it and choose “End task“.

Even if you’re not actively using certain apps, they may still be running in the background—consuming valuable system resources without your knowledge. Identifying and closing these hidden resource hogs is often the quickest way to speed up a slow PC.

2. Manage Startup Apps

Many programs automatically launch when Windows starts, slowing down boot time dramatically.

How to disable:
・In Task Manager, go to the “Startup” tab.
・Right-click any app you don’t need on startup and choose “Disable“.

3. Clear Disk Space

Low free disk space can significantly hamper performance.

Steps:
・ Open Settings > System > Storage to review free space.
・ Run Disk Cleanup by searching “Disk Cleanup” in the Start menu.
・ Select unnecessary files (e.g., temporary files) and delete.

Keeping at least 10–15% of your main system drive (usually C:) free is essential for smooth operation. When your disk is too full, Windows may struggle to manage temporary files and virtual memory efficiently.

Storage Sense (Built-In Cleanup Tool)

Turning on Storage Sense can automate cleanup:

  • Go to Settings > System > Storage.
  • Activate “Storage Sense” and adjust what it cleans and how often.

Storage Sense is especially helpful for users who often forget to manually delete temporary files or empty the Recycle Bin. Once properly configured, it can silently maintain your system’s health in the background—without requiring any extra effort.

4. Remove Large Files & Unused Programs

Look through your files—especially large ones—and delete or move them if unneeded. Also uninstall unused programs via Control Panel > Programs and Features.

5. Scan for Malware

Malware can degrade performance. Start with built-in Windows Defender:

  • Open Settings > Update & Security > Windows Security.
  • Select “Virus & threat protection” and run a scan.

If needed, install reputable security tools (e.g., Malwarebytes) to perform a deep scan.

6. Check Windows Updates

Outdated Windows can cause performance issues. Go to Settings > Update & Security > Windows Update and click “Check for updates“.

7. Turn Off Visual Effects

Windows’ fancy effects can slow older PCs. To optimize:

  • Right-click “This PC” > Properties > “Advanced System Settings”.
  • Under Performance, click “Settings…” and select “Adjust for best performance“.

While animations and transparency effects make Windows look sleek and modern, they can place unnecessary strain on older or less powerful hardware. Disabling these effects doesn’t affect functionality—it simply prioritizes performance over appearance.

8. Consider Hardware Upgrades

  • If you have ≤4 GB RAM, upgrading to 8 GB can significantly help.
  • Switching from an HDD to an SSD brings dramatic performance improvements.

Optional: Disable Hardware Acceleration in Browsers

If your browser feels sluggish when playing video or scrolling, try this:

Chrome & Edge

  1. Click the menu (⋯) → SettingsSystem.
  2. Turn off “Use hardware acceleration when available”.
  3. Restart the browser.

Firefox

  1. Menu ☰ → Settings → “General”.
  2. Uncheck “Use recommended performance settings”.
  3. Then uncheck “Use hardware acceleration when available”.
  4. Restart Firefox.

Disabling this feature reroutes display tasks from GPU to CPU. It can resolve issues caused by outdated graphics drivers ().

9. Update Graphics Drivers (Especially Intel UHD/Iris)

Outdated drivers can cause rendering issues and slowdowns. Use Device Manager (or download Intel’s Driver & Support Assistant) to update them.

Quick Comparison Table

Problem AreaWhat to Do
Background appsEnd tasks via Task Manager
Startup appsDisable unwanted ones
Low disk spaceRun Disk Cleanup and enable Storage Sense
MalwareScan with Defender or Malwarebytes
Visual effectsAdjust for best performance
Hardware acceleration (browser)Disable if browser is slow
Graphics driverUpdate via Device Manager or Intel website

This table offers a quick reference for identifying the root cause of performance issues and selecting the most effective solution. If you’re unsure where to start, begin with the top rows and work your way down until you see improvement.

Summary

By following these prioritized steps—from stopping unnecessary processes to updating drivers—you’ll likely restore your PC’s speed without buying new hardware.

Each step is easy to perform, even for beginners. Start with simple checks and progress toward more advanced options. Your PC will thank you!

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💡 Looking for more tips? Check out our full list of Windows Help Guides.