Is your Mac running slower than usual? High CPU usage often causes this problem, making your computer hot, noisy, and sluggish.
This happens when apps or system processes demand too much processing power, leaving little for other tasks.
To fix high CPU usage on your Mac, first identify the problematic process using Activity Monitor. Then, take appropriate action such as quitting the app, restarting Spotlight indexing, or removing login items that start automatically.
Hardware issues can also cause excessive CPU usage, so running Apple Diagnostics might help identify any underlying problems with your Mac’s components.
Many common culprits like the WindowServer process, corespotlightd, or resource-heavy applications can be managed with simple fixes.
By gradually quitting apps while monitoring CPU usage, you can pinpoint exactly what’s causing your Mac to work overtime and address the specific issue rather than guessing at solutions.
Step 1: Identify the Culprit Using Activity Monitor
When your Mac starts heating up, fans are roaring, or everything feels sluggish, the first step is to figure out what is eating up your CPU.
How to Check
- Open Activity Monitor (find it in Applications > Utilities).
- Click the CPU tab at the top.
- Sort the processes by % CPU to see which ones are hogging resources.
If you notice an unfamiliar app or process consuming a huge percentage of your CPU, that’s likely the root of the problem.
What You’re Looking For
- Apps stuck at 90% CPU or higher for long periods.
- Background processes (like kernel_task or mds_stores) running wild.
- Browser tabs or extensions using more than their fair share.
Step 2: Quit or Force Quit Problematic Apps
Once you spot the app causing trouble, try quitting it normally. If it doesn’t respond, you may need to force quit.
How to Do It
- In Activity Monitor, select the app.
- Click the X button at the top-left of the window.
- Choose Force Quit if it won’t close on its own.
This can instantly free up CPU resources and get your Mac running more smoothly.
Step 3: Restart Your Mac
It sounds obvious, but sometimes a simple restart clears out processes that are stuck or misbehaving. Restarting flushes temporary files and resets system resources.
Pro Tip
If you haven’t rebooted in a while, this is the easiest fix to try first—especially after major macOS updates or software installs.
Step 4: Update macOS and Apps
Outdated software can be buggy, poorly optimized, or incompatible with your system, leading to high CPU usage.
How to Stay Up to Date
- macOS: Go to System Settings > General > Software Update.
- Apps: Open the App Store and check for updates, or update apps directly through their built-in updaters.
Developers often release updates that address performance issues and CPU spikes, so keeping things current is key.
Step 5: Reset PRAM/NVRAM and SMC
If high CPU usage persists, a deeper reset might help. PRAM (Parameter RAM), NVRAM (Non-Volatile RAM), and the SMC (System Management Controller) handle low-level functions that can sometimes go haywire.
How to Reset PRAM/NVRAM
- Shut down your Mac.
- Turn it on and immediately press and hold Option + Command + P + R for about 20 seconds.
- Release the keys after you hear the startup sound or see the Apple logo twice.
How to Reset SMC
For Apple silicon Macs, simply shutting down and turning the Mac back on resets the SMC.
For Intel Macs:
- Shut down your Mac.
- Unplug the power cord for 15 seconds.
- Plug it back in and wait 5 seconds before turning it on.
Step 6: Check for Malware or Unwanted Software
Even on Macs, malware and adware can sneak in and hog system resources. If you notice suspicious processes, pop-ups, or sluggish performance, it’s worth running a scan.
Recommended Tools
- Malwarebytes for Mac (free version works fine for manual scans)
- CleanMyMac X (be selective with its features; stick to malware scanning and monitoring)
Malware or poorly written apps running in the background can cause CPU spikes and make your system overheat.
Step 7: Close Unnecessary Browser Tabs and Extensions
Browsers like Chrome, Safari, and Firefox are notorious for consuming CPU—especially if you’re running lots of tabs or extensions.
How to Cut Back
- Close tabs you’re not actively using.
- Disable or remove unnecessary extensions.
- Consider using Safari over Chrome if you’re on battery, as it’s more optimized for macOS.
Step 8: Reduce Background Processes and Login Items
Too many background processes starting up with your Mac can put a constant strain on the CPU.
How to Tame Them
- Go to System Settings > General > Login Items.
- Remove apps you don’t need at startup.
- Open Activity Monitor periodically to keep an eye on rogue background apps.
Step 9: Manage Spotlight Indexing (mds and mdworker)
If your Mac’s hard drive is constantly working and processes like mds or mdworker are consuming CPU, Spotlight may be reindexing your files.
How to Manage It
- Open System Settings > Siri & Spotlight > Spotlight Privacy.
- Add and remove problematic folders to force Spotlight to reindex them.
- If your Mac is new or you’ve just added a ton of files, give Spotlight time to finish. It usually settles down on its own.
Step 10: Check for Hardware Issues
If none of the above works, it might be a hardware problem. Failing components, like a dying fan or overheating CPU, can cause kernel_task to spike CPU usage as a protective measure.
What to Look For
- Loud fans even when doing light tasks.
- Unexpected shutdowns or reboots.
- Error reports referencing hardware issues.
Consider running Apple Diagnostics (restart and hold D key on Intel Macs, or shut down and turn on while holding Power on Apple silicon Macs) to check for hardware problems.
When to Seek Professional Help
If high CPU usage persists after trying everything, it may be time to consult an Apple Genius Bar or an authorized service provider. They can run deeper diagnostics to pinpoint hardware faults or system-level corruption.
Final Thought: Keep Monitoring and Maintain Good Habits
High CPU usage isn’t always a sign of something terrible, but it shouldn’t be ignored. Regularly monitoring your system, keeping software up to date, and practicing good habits—like closing unused apps and tabs—can go a long way toward keeping your Mac cool, quiet, and efficient.
Stay proactive, and your Mac will thank you with smoother, faster performance!
Key Takeaways
- High CPU usage causes Mac slowdowns, overheating, and reduced battery life.
- Activity Monitor helps identify resource-hungry processes that need to be addressed.
- Solutions include quitting problematic apps, removing unnecessary login items, and restarting Spotlight indexing.
Determining the Causes of High CPU Usage
Finding the root cause of high CPU usage on your Mac is essential for maintaining optimal performance.
Your system might be slowing down due to several factors that can be identified and addressed using built-in macOS tools.
Using Activity Monitor to Check CPU Usage
Activity Monitor is the most powerful diagnostic tool for identifying CPU-intensive processes on a Mac.
To access it, navigate to Applications > Utilities > Activity Monitor or use Spotlight to search for it.
Once open, click on the CPU tab at the top of the window. This tab displays a list of all running processes sorted by CPU usage.
To organize processes from highest to lowest usage, click the “% CPU” column header until the arrow points downward.
The processes consuming the most resources will appear at the top of the list. Activity Monitor also shows a CPU usage graph at the bottom of the window, displaying the overall system load.
This visual representation helps you understand whether high CPU usage is constant or occurs in spikes.
Common CPU Load Contributors
Several system processes commonly cause high CPU usage on Macs.
The spotlight indexing process (corespotlightd) often consumes significant resources when building or updating its search database, especially after installing new applications or adding files.
The kernel_task process sometimes shows high CPU usage when your Mac is managing system temperature or performing essential background tasks. This is actually a protective mechanism that throttles CPU-intensive applications to prevent overheating.
Browser applications, particularly Chrome with multiple tabs open, can be major CPU consumers. Each browser tab runs as a separate process, collectively putting strain on your system.
Background syncing services like iCloud, Dropbox, or Google Drive may cause temporary CPU spikes when synchronizing large amounts of data.
Identifying and Managing Problematic Apps
When you’ve identified CPU-hungry applications, you have several management options.
For unresponsive apps, select them in Activity Monitor and click the “X” button in the toolbar to force quit them.
Third-party utilities like App Tamer can help manage CPU usage by automatically pausing or slowing down applications when they exceed certain thresholds.
For browser-related issues, Chrome includes its own task manager (access by pressing Shift+Esc) that lets you identify which tabs or extensions are consuming the most resources.
Consider removing unnecessary startup items that automatically launch when you boot your Mac.
Go to System Preferences > Users & Groups > Login Items to manage these programs.
For Spotlight issues, you can temporarily disable indexing through Terminal or exclude certain folders from being indexed in System Preferences > Spotlight > Privacy.
