MacBook Running Slow? The Quick Check and 6 Fixes That Work

MacBook running slow? Start with the 60-second check

Before changing anything, find out what the Mac is actually struggling with. Three numbers tell you most of the story.

1. Press Command + Space, type Activity Monitor and press Return.
2. Click the CPU tab and click the % CPU column header so the busiest process is at the top. Anything sitting above 80-100% for more than a minute while you are not using it is a suspect.
3. Click the Memory tab and look at the Memory Pressure graph at the bottom. Green is fine, yellow means macOS is compressing memory, red means it is swapping to disk and you will feel it. Note the Swap Used figure next to it.
4. Open the Apple menu, choose System Settings > General > Storage and check how much space is free.
5. Check the battery icon in the menu bar. If it is yellow, Low Power Mode is on.

Match what you saw to the table:

For a full walkthrough of the Memory tab, read How to Check RAM Usage on Mac.

Cause 1: Browser tabs are eating your memory

This is the most common reason a MacBook slows down, especially on 8 GB and 16 GB models. Every open tab keeps its own process alive, and modern web apps like Gmail, Slack, Figma, Notion and Google Docs can each hold hundreds of megabytes even when you have not looked at them in hours. In Activity Monitor this shows up as dozens of Google Chrome Helper (Renderer) or similar entries.

Quick fixes

1. Turn on Chrome Memory Saver. In Chrome, open Settings > Performance and switch on Memory Saver. Chrome will discard tabs it decides are inactive. Edge has a similar option called Sleeping Tabs.
2. Try a tab discard extension. Extensions in the "auto tab discard" category let you set your own timer and whitelist sites.
3. Close tabs you truly do not need. Bookmark a group with Command + Shift + D before closing it so nothing is lost.

The catch

Built-in tab savers work per browser, and many people run two or three browsers at once. Extensions also cannot see how much memory the whole Mac has left, so they cannot react when pressure spikes.

This is the problem Mac Ninja was built for. It unloads tabs untouched for 15 minutes (adjustable), and sooner when memory is tight, in Chrome, Brave, Edge, Arc, Vivaldi, Opera, Comet, Dia, Chromium and Safari (Lite mode). The tabs stay in your tab strip and reload when you click them. The visible tab in each window, pinned tabs, tabs playing sound, incognito windows, pages still loading and sites you protect are always skipped. The optional free Mac Ninja Helper extension uses Chrome's native tab discarding, the same mechanism as Memory Saver.

Cause 2: A background app is hogging the processor

If one process sits at the top of the CPU tab while you are not using it, that app is taking processor time away from the one you are working in. On a MacBook it also drains the battery and spins up the fans.

Common culprits and what to do

• mds_stores, mdworker (Spotlight): indexing after a macOS update or after copying lots of files. Leave the Mac plugged in and awake for an hour; it finishes on its own.
• photoanalysisd (Photos): scanning faces and objects after an import. Same fix: let it finish while plugged in.
• bird, cloudd, Dropbox, Google Drive, OneDrive: syncing. Pause sync from the app's menu bar icon during heavy work.
• backupd (Time Machine): a backup in progress. Let it run, or skip one from the Time Machine menu.
• WindowServer: high when driving external displays or many windows. Close unused windows or lower scaled resolutions.
• Zoom, Teams, Adobe updaters, game launchers: often busy in the background. Quit them from their menu bar icon when not needed.

To stop something right away, select it in Activity Monitor and click the Stop (X) button, then Quit. Do not force quit system processes you do not recognize.

Quitting works, but you lose what was open and the app often restarts later. Mac Ninja takes a gentler route with Foreground Boost: background apps that hog the processor or disk are moved to macOS's own low-priority lane and get full speed back the instant you switch to them. It never slows apps playing or recording audio, so your call or music keeps going.

Cause 3: Heat, a loud fan and thermal throttling

When a MacBook gets hot, macOS lowers processor speed to protect the chip. The result is a Mac that starts fast and gets slower the longer you work. A loud fan on a MacBook Pro, or a hot keyboard on a fanless MacBook Air, is the giveaway. A process called kernel_task using lots of CPU is often macOS deliberately holding the processor back to cool it.

Fixes

1. Get it off soft surfaces. Beds, couches and laps block airflow. A desk or a stand makes a measurable difference.
2. Find the heat source. Heat is usually Cause 2 in disguise: a runaway background process. Check the CPU tab first.
3. Watch the Energy tab. In Activity Monitor, the Energy tab shows which apps use the most power, which roughly tracks heat.
4. Clean the vents on older Intel MacBook Pros, where dust builds up over years.

For a deeper look, including sensors and when to worry, see MacBook Overheating? How to Find the Cause and Cool It Down.

Cause 4: Battery, charger and power settings

A MacBook that is only slow on battery is usually doing exactly what it was told. Low Power Mode deliberately reduces performance to stretch battery life.

Check these settings

1. Open System Settings > Battery and look at Low Power Mode. Options include Never, Always, Only on Battery and Only on Power Adapter. Set it to Never when you need speed.
2. On the same page, click the info button next to Battery Health. If it says Service Recommended, a worn battery can cause slowdowns and sudden shutdowns. Apple or an authorized provider can replace it.
3. Check your charger. Hold Option, open the Apple menu and choose System Information > Power. The Wattage line shows what the adapter is delivering. A low-wattage phone charger may not keep up under load, so the battery drains and the Mac throttles.

Reset power management

On Apple Silicon Macs, shut down, wait 30 seconds and start up again; that resets power management. On Intel MacBooks with a T2 chip, Apple documents an SMC reset that is worth trying if fans or charging behave oddly.

Cause 5: The startup disk is nearly full

macOS needs free space for swap, caches and updates. When the disk drops below roughly 10-15% free, everything slows down, and it hits hardest on MacBooks with 8 GB of memory, which lean on swap more.

Free up space

1. Open System Settings > General > Storage and review the Recommendations: Store in iCloud, Optimize Storage and Empty Trash Automatically.
2. Click the info button next to each category (Applications, Documents, iOS Files, Developer) to find the biggest items.
3. Delete old iPhone backups, downloaded installers in Downloads, and large videos you have already archived.
4. Empty the Trash.

Mac Ninja helps here only in a limited way, and it is worth being clear about that. When the disk is nearly full (less than 10% or 20 GB free), its Offload Unused Apps feature packs apps you have not opened in 60 days into a small stand-in that unpacks the same app when you open it. In testing, a 386 MB app took 71% less room and was back in 2 seconds. It does not touch photos, videos or documents, so if those are filling your disk, the steps above are what fixes it.

Cause 6: Login items, pending updates or aging hardware

If none of the above stands out, work through these in order.

1. Restart. Many people never do. A restart clears swap and stuck processes. Use Apple menu > Restart.
2. Trim login items. Open System Settings > General > Login Items & Extensions (called Login Items on macOS 14 Sonoma). Remove apps you do not need at startup and switch off background items you do not recognize.
3. Update macOS. Go to System Settings > General > Software Update. macOS 26 Tahoe, macOS 15 Sequoia and macOS 14 Sonoma all receive performance and bug fixes. Expect a day of Spotlight indexing after a big update.
4. Try Safe Mode. On Apple Silicon, shut down, hold the power button until startup options appear, select your disk, hold Shift and click Continue in Safe Mode. On Intel, hold Shift while restarting. If the Mac is fast in Safe Mode, a login item or extension is to blame.

Some MacBooks are simply slow for today's software. An Intel MacBook Air with 8 GB of memory will struggle with modern web apps no matter what you tweak. No app can make an old processor faster; at that point the real fix is new hardware.

How to stop your MacBook slowing down again

Most MacBooks slow down again within days because the causes return: tabs pile up, sync apps wake up, an updater starts churning. Prevention means handling those automatically so you do not have to babysit Activity Monitor.

• Keep 15-20% of storage free and turn on Empty Trash Automatically.
• Set Low Power Mode to Only on Battery rather than Always.
• Restart once a week.
• Review login items after installing new apps.
• Let tabs sleep instead of closing them by hand.

Mac Ninja covers the last two causes that keep coming back. It sits in the menu bar, unloads idle tabs across your browsers, calms background CPU hogs with Foreground Boost (adapting to battery, Low Power Mode and heat), and never closes an app or a normal tab. If you use AI browser agents such as Claude in Chrome, the helper also closes tabs those agents leave behind after the session has been idle for 8 hours (configurable, can be turned off).

Right-click the menu bar ninja for a dashboard showing memory pressure, the heaviest apps with their energy use in watts, apps keeping the Mac awake, and apps idle for hours holding memory. Why does my Mac feel slow right now? gives a plain-English reading of the live numbers, phrased on-device by Apple Intelligence on macOS 26 and later. There is no account and no tracking; see the privacy policy.

Who it is not for: if your disk is full of photos and video, or your MacBook is an older Intel model that is slow even with nothing open, Mac Ninja will not fix that. If you want a full cleaning and uninstall suite, compare options in Best Mac Cleaner in 2026.

What to do next

1. Run the 60-second check above and note which cause matches.
2. Apply that fix first; most MacBooks recover with one change.
3. If tabs or background apps were the problem, download Mac Ninja's free 7-day trial and work normally for a few days. Plans are $9.99 per year or $24.99 once, each for up to 3 Macs, with a 14-day money-back guarantee (see pricing).
4. For help allowing browser access or installing the Chrome helper, visit support.