Common reasons your computer slows down
A slow computer usually comes from one of four sources: too many programs running at once, a hard drive that is nearly full, malware or unwanted software, or a failing hard drive. The first three are fixable in minutes or hours. The fourth requires replacement, but you can test for it before spending money.
Most people notice slowness when opening files, switching between programs, or during startup. The speed drops because your processor is waiting for data from storage, or because RAM (the temporary memory your computer uses while working) is exhausted and the system is using your hard drive as a substitute, which is much slower.
Key Takeaways
- Check how much hard drive space is free by opening File Explorer (Windows) or Finder (Mac) and looking at your main drive — if less than 10 percent is free, delete old files or programs.
- Open Task Manager (Windows) or Activity Monitor (Mac) to see which programs are using the most CPU and memory; close or uninstall the ones you do not use.
- Restart your computer, which clears temporary files and stops background processes that accumulate over time.
- Run a malware scan using Windows Defender (built into Windows) or a free tool like Malwarebytes to check for unwanted software.
- If your hard drive is making clicking or grinding sounds, or if slowness began suddenly after a drop or impact, the drive may be failing and needs professional recovery or replacement.
Check how much storage space you have left
When your hard drive is more than 90 percent full, Windows and Mac both slow down because the operating system needs free space to write temporary files while you work. Open File Explorer on Windows or Finder on Mac, click on your main drive, and look at the storage bar at the bottom of the window.
If the bar is nearly full, delete files you no longer need — old downloads, duplicate photos, or videos you have backed up elsewhere. You can also uninstall programs you do not use. On Windows, go to Settings > Apps > Apps and Features, find the program, and click Uninstall. On Mac, open Applications, drag unused programs to the Trash, and empty it.
Aim to keep at least 10 to 15 percent of your drive free. If you are close to that and do not want to delete files, an external hard drive or cloud storage (Google Drive, OneDrive, iCloud) can hold old files without slowing your computer.
Stop programs from running in the background
Many programs start automatically when you turn on your computer and keep running even when you are not using them. Each one uses a small amount of memory and processor power. Over time, this adds up and slows everything down.
On Windows, press Ctrl + Shift + Esc to open Task Manager. Click the Processes tab and look at the CPU and Memory columns. Programs using more than 10 to 15 percent of either are worth investigating. Right-click one and choose End Task to close it when ready. To stop it from starting next time, go to Settings > Apps > Startup and toggle off programs you do not need.
On Mac, press Command + Space, type Activity Monitor, and press Enter. Click the CPU or Memory tab to sort by usage. Select a program and click the X button to close it. To prevent it from opening at startup, go to System Settings > General > Login Items and remove it from the list.
Restart your computer
A restart clears temporary files, stops background processes that have accumulated, and refreshes your computer's memory. Many slowness problems disappear after a restart because programs that were using resources are closed and the system starts fresh.
Restart at least once a week, or whenever you notice slowness. If your computer has been on for weeks without restarting, slowness is almost certainly the cause. Save your work, click the Start menu (Windows) or Apple menu (Mac), and select Restart.
Scan for malware and unwanted software
Malware, spyware, and adware run in the background and consume CPU, memory, and internet bandwidth. They can also hijack your browser, change your search engine, or display constant pop-ups. Windows Defender, built into Windows 10 and 11, can catch most of these. Open Windows Security, click Virus and Threat Protection, and run a Quick Scan.
If you want a second opinion or suspect a serious infection, read Malwarebytes (the free version is sufficient). Install it, open it, and run a Full Scan. This takes 10 to 30 minutes depending on how much data you have. Restart your computer when it finishes.
On Mac, malware is less common, but you can still run a scan. Open System Settings, click General > Software Update to make sure your operating system is current, then use a free tool like Malwarebytes for Mac if you suspect infection.
Test your hard drive for failure
If slowness started suddenly, or if your computer makes clicking, grinding, or beeping sounds, your hard drive may be failing. A failing drive reads and writes data slowly or unreliably, which makes everything feel frozen.
On Windows, open Command Prompt as Administrator (right-click and choose Run as Administrator), type wmic logicaldisk get name, and note your drive letter. Then type chkdsk C: (replace C with your drive letter) and press Enter. Windows will ask if you want to schedule a check on the next restart — say yes. Restart your computer and let it run. This takes 30 minutes to several hours depending on drive size.
On Mac, restart your computer and hold Command + S while it boots. Type fsck -fy and press Enter. Wait for the scan to finish. If it reports errors, your drive may need repair or replacement.
If the scan shows errors, or if the drive is making noise, back up your files when ready to an external drive or cloud storage. A failing drive can stop working without warning. Contact a local computer repair shop for professional recovery or replacement.
When to replace your computer
If your computer is more than 7 to 10 years old, slowness may be normal wear. Hard drives, SSDs (solid-state drives), and batteries all degrade over time. If you have tried the steps above and slowness persists, or if a technician tells you the hard drive is failing, replacement is usually cheaper than repair.
Before you buy a new computer, decide what you use it for. A basic laptop for email, web browsing, and documents costs $300 to $600. A computer for photo or video editing, gaming, or programming costs $800 to $2,000 or more. Visit a local electronics store and ask to try a few models to see what feels fast enough for your work.
Frequently Asked Questions
How do I know if my hard drive is failing?
A failing drive usually makes clicking, grinding, or beeping sounds. It may also freeze randomly, take a long time to open files, or show error messages about corrupted files. If you hear noise or see these signs, back up your files when ready and have a technician check it.
Will adding more RAM make my computer faster?
Only if your computer is running out of memory. Open Task Manager (Windows) or Activity Monitor (Mac) and check the Memory tab. If it shows 90 percent or higher while you are working normally, more RAM would help. If it shows 50 to 70 percent, RAM is not the problem.
Should I use a cleaning program to speed up my computer?
Most cleaning programs do not help and some are malware. Restarting your computer, uninstalling unused programs, and deleting old files do the same job safely. Avoid programs that promise to "clean your registry" or "optimize your system" unless a technician you trust recommends one.
Can I upgrade my computer instead of replacing it?
If your computer is 5 to 7 years old, upgrading the hard drive to an SSD (solid-state drive) often makes the biggest difference in speed. A technician can install one for $100 to $300 in labor plus the cost of the drive. Adding RAM is also possible but less common on newer laptops.
Why is my computer slow only when I use certain programs?
Some programs are resource-heavy — video editors, games, and design software need a lot of CPU and memory. If your computer slows only when you open one program, that program may need more power than your computer has. Close other programs while using it, or consider upgrading if you use it often.