How to Fix High CPU Usage and Speed Up a Slow Computer

My own Windows PC showed 95% CPU last week even when I was doing nothing. I opened Task Manager with Ctrl+Shift+Esc and found Chrome was using 60% CPU because of 15 open tabs. Here is how I fixed it without installing any PC cleaner.

How do you find what is using your CPU?

Task Manager is the best first check for many Windows performance problems. It shows which apps and processes are using CPU, memory, disk, and other resources.

1. Press Ctrl + Shift + Esc to open Task Manager.
2. Select More details if the compact window appears.
3. Open the Processes tab.
4. Click the CPU column heading to sort processes by CPU usage.
5. Watch the list for a minute and note which process stays near the top.

A short CPU spike can be normal when an app starts, a video plays, or Windows performs maintenance. Look for usage that remains high while the computer is idle or while you perform simple tasks.

Do not automatically select End task for every process using a lot of CPU. Save open files first. Close an app you recognise and are not using. If the process name is unfamiliar or appears to belong to Windows, search for its exact name before stopping it.

Which startup apps should you disable?

Some apps start automatically when you sign in to Windows. Chat apps, game launchers, music players, and update helpers may run even when you do not need them. Too many startup apps can slow sign-in and add background activity.

1. Open Task Manager with Ctrl + Shift + Esc.
2. Select Startup apps. In some Windows versions, this may appear as a Startup tab.
3. Review the app name and Startup impact.
4. Right-click a non-essential app and select Disable.
5. Restart the PC and check whether performance improves.

Disable only apps you recognise and do not need at startup. Do not disable security software, touchpad or audio utilities, or unfamiliar hardware-related items without checking their purpose. Disabling an app from startup does not uninstall it; you can still open it manually.

For Microsoft's step-by-step guidance, see Microsoft Support, Configure Startup Applications in Windows.

How can browser tabs and extensions slow your computer?

A browser can use significant CPU and memory when many tabs, video streams, web apps, or extensions are active. Test the browser before assuming the whole computer is faulty.

1. Save work in open web apps.
2. Close tabs you no longer need.
3. Open the browser's task manager, if available, to identify a busy tab or extension.
4. Disable extensions you do not recognise or no longer use.
5. Restart the browser and compare CPU usage.

In Chrome, open Settings, then Performance, and review Memory Saver. This feature deactivates some inactive tabs to save memory. It can help on a memory-limited computer, but it is not a guaranteed fix for high CPU usage. A page or extension that keeps using CPU may need separate attention.

For more detail, see Google Chrome Help, Personalize Chrome Performance.

What should you do if Windows Search uses high CPU?

Windows Search builds an index so Windows can find files more quickly. Indexing may use more resources while it is first building an index or processing many file changes. Avoid disabling services at random.

1. Open Settings.
2. In Windows 11, select Privacy & security, then Searching Windows.
3. In Windows 10, open Settings, then Search, then Searching Windows.
4. Review whether Classic or Enhanced indexing is selected.
5. If you do not need your whole PC indexed, consider limiting indexed locations.

Allow indexing time to finish, then check Task Manager again. Do not treat Windows Search and SysMain as the same service. They perform different functions, and changing service startup types without a clear reason can create other problems.

See Microsoft Support, Search Indexing in Windows for details about indexing modes and resource use.

Could heat or dust be making your PC slow?

Processors produce heat during work. If a laptop or desktop cannot cool itself properly, it may reduce performance to control temperature. Dust, blocked vents, a failing fan, or a hot room can contribute to cooling problems.

• Place a laptop on a hard, flat surface.
• Keep air vents clear of fabric and other obstructions.
• Check whether the fan is blocked, unusually noisy, or not spinning when expected.
• Shut down and unplug the computer before cleaning external vents.
• Get professional help if the device overheats repeatedly or the fan appears damaged.

Do not open a device or use liquid cleaners unless you know how to do so safely. For a practical cleaning guide, see how to clean dusty PC fans without static damage. If the fan is loud but temperatures seem normal, compare the symptoms with a guide to a loud laptop fan with normal temperatures.

Can antivirus software or malware cause high CPU usage?

Yes, but high CPU usage alone does not prove that a computer has malware. Security scans, software updates, and legitimate background tasks can also use CPU for a while.

1. Check the process name in Task Manager.
2. Install Windows and security updates through the normal Windows settings.
3. Run a scan with Windows Security or another reputable security product.
4. Remove unfamiliar apps only after checking what they are.
5. Avoid running two real-time antivirus products together unless their vendors explicitly support that setup.

Do not download a random “PC booster” or registry cleaner that promises instant speed. Unverified system tools may make unwanted changes or bundle unwanted software. If a security app reports a threat, follow its removal instructions and restart the PC if requested.

If you suspect a malicious app or unauthorised access, see how to recognntLook at the top three items on that listise possible spyware or hacking signs for related device-security guidance. That article concerns phones, so use Windows Security for a Windows PC.

Should you change virtual memory or defragment a drive?

These steps address different issues. Virtual memory helps Windows manage memory pressure, while drive optimisation is designed for the storage device. Neither is a guaranteed cure for high CPU usage.

To review virtual memory, search Windows for View advanced system settings. Under Performance, select Settings, open Advanced, then select Change under Virtual memory. If you do not have a specific reason to change the paging file, leave Automatically manage paging file size for all drives selected.

To check a drive, search for Defragment and Optimize Drives and open the tool. Windows handles traditional hard-drive defragmentation and SSD optimisation differently. Do not use a third-party defragmenter or force repeated defragmentation as a general CPU fix.

See Microsoft Support, Defragment and Optimize Your Data Drives in Windows.

What if CPU usage is still high after these fixes?

If the problem continues, use this order to narrow it down. Change one thing at a time so you can tell which step helped.

1. Restart once: save your files and restart Windows normally.
2. Wait for background work: after updates or first-time indexing, let the process finish and check usage again.
3. Test without optional startup apps: disable only recognised, non-essential apps and restart.
4. Check for malware: run a scan with Windows Security.
5. Check memory and disk: if these are also near capacity, close apps or investigate storage pressure.
6. Look for a repeating process: note its exact name and search for reliable guidance before changing it.
7. Seek repair help: repeated shutdowns, unusual heat, or persistent performance loss may need hardware diagnosis.

If the computer becomes slow only when you browse the web, test another browser and review extensions. If offline apps also lag, the cause may be local to Windows, the hardware, or another background process. If only websites load slowly while offline apps work normally, investigate the network as well. See how to diagnose Wi-Fi speed problems.

When you need to free storage, remove files you no longer need and uninstall unused apps carefully. Storage cleanup can help when the drive is nearly full, but it will not automatically fix every CPU problem. See how to free up storage on a full laptop.

Which common fixes should you avoid?

• Do not end unfamiliar system processes: identify them first.
• Do not install registry cleaners at random: they can cause unwanted changes.
• Do not disable Windows updates permanently: updates include security and reliability fixes.
• Do not overclock to solve unexplained lag: extra heat and instability can make the problem worse.
• Do not assume every CPU spike is malware: check the process and its activity first.

Windows updates may temporarily use system resources, but disabling them indefinitely is not a safe general performance strategy. If an update appears stuck or repeatedly causes high usage, check Windows Update status and seek guidance for the exact error or process.

Common questions about high CPU usage

Is 100% CPU usage always bad?

No. A short spike during a demanding task can be normal. Persistent high usage while idle or doing simple work deserves investigation.

Will adding more RAM fix high CPU usage?

Not necessarily. More RAM can help when memory is the limit, but it does not make the processor itself faster.

Does Chrome Memory Saver reduce CPU usage?

It mainly reduces memory use by deactivating some inactive tabs. It may help overall responsiveness, but a CPU-heavy tab or extension still needs attention.

Can a virus make the fan run all day?

Malware can use CPU in the background, but a loud fan can also result from updates, demanding apps, dust, or poor cooling. Run a security scan and check temperatures and processes.

How long should I wait before treating high CPU usage as a problem?

There is no single time limit for every PC. If usage remains high after startup activity settles and no demanding app is running, investigate the process instead of relying on a fixed percentage or time alone.

What should you do first to speed up your computer?

Start with Task Manager. Find the process using the most CPU, check whether you recognise it, and close only an app you can safely stop. Next, review startup apps and browser extensions. If the problem remains, check Windows indexing, updates, security, memory, and cooling one at a time.

You do not need to buy a new computer or install a “booster” before identifying the cause. If the PC still runs slowly, record the process name and the CPU, memory, and disk readings, then use those details to choose the next troubleshooting step.

Disclaimer

This article provides general information for troubleshooting Windows performance. Save your work before closing apps or changing settings. If you are unsure whether a process is essential, do not stop it until you have identified it.