This checklist helps you find and fix the most common causes of a slow Mac, from full storage and memory pressure to background processes and thermal throttling. Work through the steps in order, testing the Mac after each one, and you will usually resolve the slowdown without reinstalling macOS.
Before You Start
Take two minutes to check the basics, because they cause a surprising number of “my Mac is slow” complaints. First, confirm the Mac is running a recent version of macOS: click the Apple menu and choose About This Mac, then check the version number. Second, make sure the Mac has been restarted in the last few weeks; macOS relies on background maintenance tasks that only run during idle time, and a long uptime can leave stale caches and half-finished updates behind. Finally, check that the power adapter is plugged in for a MacBook, because many Macs intentionally slow the CPU on battery to save energy. If the Mac is already on AC power and restarted recently, move on to the next section.
Check Storage Space
macOS needs free space for virtual memory, temporary files, and system caches. When the startup disk is nearly full, the Mac can become dramatically slower, and some apps may refuse to open. Apple recommends keeping at least 10–20% of the disk free, so on a 256 GB drive that means 25–50 GB available. To check, click the Apple menu and choose About This Mac, then go to the Storage tab. If the bar is mostly red, free space by emptying the Trash, deleting large downloads, and moving photos or videos to an external drive. You can also use the built-in Storage Management tool (About This Mac > Storage > Manage) to see which files and apps take up the most space. A quick way to reclaim space is to clear the system cache folder: open Finder, press Shift+Cmd+G, type ~/Library/Caches, and delete the contents of any folders you do not recognize. Do not delete the folders themselves, only the files inside. This is safe for most users, but if you are unsure, skip it and use the Storage Management tool instead.
Check Memory Pressure
Memory pressure is a more accurate indicator of RAM usage than the “Memory Used” percentage, because macOS aggressively caches files in unused RAM to speed things up. To see it, open Activity Monitor (in Applications/Utilities), click the Memory tab, and look at the graph at the bottom. If it is green, the Mac has enough RAM. If it is yellow or red, the system is swapping memory to the SSD, which causes noticeable slowdowns. To reduce memory pressure, quit apps you are not using, especially web browsers with many open tabs, and check for memory leaks by sorting processes by the Memory column. A single app using tens of gigabytes usually indicates a leak, and quitting it will free the memory. If memory pressure is constantly red with normal use, the Mac likely needs more RAM, but on many modern Macs the RAM is soldered and cannot be upgraded. In that case, consider using fewer apps at once, or upgrading to a Mac with more memory.
Check CPU and Energy Usage
High CPU usage from a single process can make the whole system feel sluggish. In Activity Monitor, click the CPU tab and sort by the % CPU column. If one process is using over 100% (which means multiple cores), it may be stuck or doing heavy work. Common culprits are web browsers with many tabs, video conferencing apps, and background updaters. If you see a process you do not recognize, search for its name online before quitting it, because some system processes are essential. You can also check the Energy tab to see which apps are using significant energy, which is especially important on a MacBook. To quit a misbehaving process, select it and click the X button, then confirm. If the Mac still feels slow, check the Activity Monitor history graph (Window > CPU History) to see if the slowdown is constant or only during certain tasks.
Check Login Items and Background Processes
Many apps install login items that launch automatically when you start the Mac, and they can eat CPU and memory before you even open anything. To review them, go to System Settings > General > Login Items (on older macOS, System Preferences > Users & Groups > Login Items). You will see two lists: Login Items and Allow in the Background. Remove any apps you do not need at startup by selecting them and clicking the minus button. Be careful not to remove system components like the macOS helper processes. Also check the Background Items list, which shows apps that run in the background even when you are not using them. Disable anything you do not recognize or no longer use, but keep items from your antivirus or security software. After removing login items, restart the Mac and see if the startup time and overall responsiveness improve.
Check for Thermal Throttling
If the Mac gets hot, it may slow down the CPU to prevent damage, a process called thermal throttling. This is common on MacBooks when they are used on soft surfaces like a bed or a pillow, which block the vents. To check if this is happening, download a free app like Intel Power Gadget (for Intel Macs) or use the built-in Activity Monitor to look at the CPU usage and temperature. If the CPU usage is high but the temperature is above 90°C (194°F) and the fan is spinning loudly, the Mac is likely throttling. To fix this, move the Mac to a hard, flat surface, ensure the vents are not blocked, and consider using a laptop stand with better airflow. On a MacBook, you can also reset the SMC (System Management Controller) to restore normal fan and thermal management, but the steps vary by model and chip, so check Apple’s support site for instructions. On Apple Silicon Macs, there is no SMC reset, but restarting the Mac can help clear temporary thermal issues.
Check for Malware and Adware
While macOS is relatively secure, malware and adware can still slow down a Mac by running background processes that mine cryptocurrency or display ads. Symptoms include a sudden drop in performance, new toolbars in the browser, or a homepage you did not set. To check, open Activity Monitor and look for processes with names like “CoinMiner” or “WebAdvisor,” but be careful because legitimate apps can have similar names. You can also use a reputable antivirus app, but avoid free ones that bundle adware themselves. If you suspect malware, the safest fix is to remove the offending app and its login items, then restart the Mac. In severe cases, you may need to reinstall macOS, but that is a last resort. Always download apps from the Mac App Store or the developer’s official website, and never install software from pop-up ads.
Frequently Asked Questions
Why is my Mac slow after an update?
macOS runs background tasks like Spotlight indexing and photo analysis after an update, which can use CPU and memory for a few hours or even a day. This is normal, and the Mac should speed up once the tasks finish. If it stays slow for more than a day, check Activity Monitor to see if a process like “mdworker” or “photoanalysisd” is stuck, and restart the Mac to force the tasks to start over.
How do I clear RAM on a Mac?
You cannot manually clear RAM on macOS, and you do not need to, because the system manages memory automatically. If memory pressure is high, the best fix is to quit apps you are not using, or restart the Mac to reset all processes. There is no built-in “clear RAM” button, and third-party “memory cleaner” apps are unnecessary and can sometimes cause problems.
Does closing apps speed up my Mac?
Yes, but only if the apps are using significant CPU or memory. A single app that is idle uses very little resources, so closing it will not help much. The key is to close apps that are actively using CPU (check Activity Monitor) or that have memory leaks. Closing browser tabs is often more effective than quitting the browser itself, because each tab can use hundreds of megabytes.
How much free space does a Mac need?
Apple recommends keeping at least 10–20% of your startup disk free, which is about 25–50 GB on a 256 GB drive. This space is used for virtual memory, temporary files, and system caches. If you drop below that, you may see performance issues and “Your disk is almost full” warnings. If you are close to the limit, offload large files to an external drive or cloud storage.
Is it safe to delete caches on a Mac?
Yes, deleting the contents of the user cache folder (~/Library/Caches) is generally safe, because apps will recreate the files they need. However, do not delete the folder itself, and avoid deleting caches in the system folder (/Library/Caches) unless you are comfortable with the risk. If an app misbehaves after you clear its cache, restart the app or the Mac, and it will usually rebuild the cache.
Why is my Mac slow when it is low on battery?
macOS automatically reduces CPU performance on battery to extend battery life, so the Mac may feel slower when unplugged. This is normal, and you can improve performance by plugging in the power adapter. You can also check the Energy Saver settings (System Settings > Battery) to see if there is an option to prioritize performance, but this may drain the battery faster.
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