What CPU cache is and why clearing it sometimes helps

CPU cache is a small amount of very fast memory built into your processor that stores copies of data your computer uses frequently. Think of it like a notepad next to your desk instead of a filing cabinet across the room — your processor checks the cache first before going to slower main memory. This is normal and good; cache makes your computer faster.

Most of the time, you should not clear your CPU cache. The processor manages it automatically and clearing it actually slows things down temporarily. But in specific situations — after a major software update, when your computer is running unusually hot, or when you are troubleshooting a freezing or crashing problem — clearing the cache can help reset things to a clean state.

The catch is that you cannot directly clear CPU cache the way you clear a read folder. What you can do is clear related caches that sit between your CPU and main memory, or restart your computer (which clears everything). The method depends on what operating system you use and what problem you are trying to solve.

Key Takeaways

  • CPU cache is managed automatically by your processor and clearing it is rarely necessary for normal use.
  • Restarting your computer clears all caches and is the simplest troubleshooting step when performance drops.
  • On Windows, clearing the disk cache through Settings or using the Disk Cleanup tool can help after updates or when storage is full.
  • On Mac, restarting or using Terminal commands like purge can clear memory caches when your computer is running slowly.
  • If your computer is overheating, clearing cache will not fix the problem — check for dust in vents and make sure fans are running.

Restart your computer first

The fastest and most effective way to clear cache is to shut down and restart your computer. When you power off, all cache — CPU cache, disk cache, and memory cache — is cleared automatically. When you power back on, your computer starts fresh.

This is also the safest method because it does not require you to dig into system settings or run commands. If your computer is running slowly, freezing, or crashing, restart it before trying anything else. Wait for it to fully shut down (do not force it off), then wait 10 seconds before turning it back on. This gives capacitors time to discharge.

If restarting does not solve the problem after a few hours of use, the issue is likely not cache-related. Move on to the other methods below or check whether a specific program is using too much CPU or memory.

Clear disk cache on Windows

Windows stores copies of files you use often in a disk cache to speed up access. You can clear this through the Disk Cleanup tool. Open Settings, go to System, then Storage. Scroll down and click "Temporary files." You will see a list of cache types — check the boxes next to "Temporary files," "Recycle Bin," and "Temporary internet files," then click Delete.

Alternatively, you can use Disk Cleanup directly. Press Windows key + R, type cleanmgr, and press Enter. The tool will scan your drive and show you what can be deleted. Check the boxes for cache-related items and click OK. This is especially useful after a Windows update, when old cache files can take up significant space.

Do not check boxes for items you are unsure about — stick to temporary files and cache. Deleting system files or driver files can cause problems. If you are not comfortable using these tools, restarting your computer alone will clear most cache without any risk.

Clear memory cache on Mac

Mac automatically manages memory cache, but you can force it to clear using the Terminal. Open Terminal (search for it in Spotlight), then type purge and press Enter. This command clears unused memory and forces the system to reload what it needs. You will not see any confirmation message — just wait for the command prompt to return.

You can also clear the browser cache, which is separate from CPU cache but affects overall performance. In Safari, go to History menu and click "Clear History," then choose how far back to clear. In Chrome, press Ctrl + Shift + Delete (or Cmd + Shift + Delete on Mac), select "All time," and click Clear Data.

Like Windows, the most reliable method on Mac is still a full restart. If your Mac is running slowly, shut it down completely, wait 10 seconds, and turn it back on. This clears all caches and often solves performance problems without needing Terminal commands.

When clearing cache will not help

If your computer is overheating, clearing cache will not fix it. Overheating is usually caused by dust blocking air vents, a failing fan, or a program using the CPU constantly. Check whether your computer feels hot to the touch, listen for loud fan noise, and look at the vents — if they are clogged with dust, use compressed air to clean them gently.

If your computer is slow because a specific program is using too much memory or CPU, clearing cache will not stop that program. Open Task Manager on Windows (Ctrl + Shift + Esc) or Activity Monitor on Mac (Cmd + Space, then type "Activity Monitor") and look at the CPU and Memory columns. If one program is using 80% or more, that is your problem — close it or uninstall it if it keeps happening.

If your hard drive is almost full, clearing cache helps a little but the real solution is to delete large files you do not need or move them to external storage. Cache is usually only a few gigabytes; if your drive is 90% full, you need to free up much more space than cache clearing will provide.

What to do if your computer is still slow after clearing cache

If you have restarted, cleared cache, and your computer is still running slowly, the problem is likely something else. Check how much free space you have on your hard drive — if it is below 10%, your computer will slow down significantly. Delete old files, empty the Recycle Bin or Trash, and move large files like videos to external storage.

Look at what programs start when your computer boots. On Windows, open Task Manager, go to the Startup tab, and disable programs you do not need running all the time. On Mac, go to System Settings, General, Login Items, and remove programs from the list. Too many startup programs can make your computer slow to boot and slow to use.

If slowness started after installing new software, try uninstalling it. If it started after a Windows or Mac update, check that the update finished completely — sometimes updates run in the background for hours. If nothing works, your hard drive may be failing or your computer may have malware; consider taking it to a technician or running a full antivirus scan.

Frequently Asked Questions

Is it safe to clear CPU cache?

Yes, clearing cache is safe. Your computer will temporarily run slightly slower while it rebuilds the cache, but no data is lost and no settings are changed. Restarting your computer is the safest method because it does not require any manual steps.

How often should I clear my cache?

You should not clear cache on a regular schedule. Clear it only when troubleshooting a specific problem — slowness, freezing, or after a major software update. For daily use, let your computer manage cache automatically.

Will clearing cache free up space on my hard drive?

Yes, clearing disk cache and temporary files can free up a few gigabytes, especially after updates. However, if your drive is nearly full, you will need to delete much larger files like old videos, downloads, or programs you no longer use.

What is the difference between CPU cache and disk cache?

CPU cache is built into your processor and stores data your processor uses right now. Disk cache is stored on your hard drive and stores copies of files you use often. You cannot directly clear CPU cache, but restarting clears both.

Can I clear cache without restarting?

Yes. On Windows, use Disk Cleanup or the Temporary Files settings. On Mac, use the purge command in Terminal or clear your browser cache. Restarting is more thorough, but these methods work without shutting down.