Tidy MacMost slow Macs have one of four causes: an app or browser tab using the processor, too little memory so macOS swaps to disk, a nearly full disk, or background work after an update. Check Activity Monitor’s CPU and Memory tabs, keep at least 10–15% of your disk free, remove login items you don’t need, and restart.
- Restart your Mac.
- Open Activity Monitor and sort the CPU tab by % CPU; quit what’s busy.
- Check Memory Pressure on the Memory tab; quit memory-heavy apps and tabs.
- Free up disk space so at least 10–15% of the disk is free.
- Remove login items and background apps you don’t need.
- Close heavy browser tabs and remove extensions you don’t use.
- Let indexing and photo analysis finish after an update.
- Install macOS and app updates.
- Run Disk Utility First Aid, then try Safe Mode to rule out startup software.
Start with a restart
It sounds too simple, but a restart clears swap files, stuck processes and memory leaks in one go. If your Mac has been on for weeks, do this first.
1. Find what's using the processor
Open Activity Monitor (Applications › Utilities) and choose CPU. Sort by % CPU. Values above 100% are normal for busy apps on multi-core Macs. If something you aren't using sits near the top, quit it (select it, then the ✕ button). Browser tabs often show up as separate "Web Content" or "Helper (Renderer)" processes.
2. Check memory pressure, not "memory used"
On the Memory tab, look at the Memory Pressure graph at the bottom. Green is fine, even if "Memory Used" looks high: macOS deliberately fills spare memory with cache. Yellow or red means apps want more memory than you have, and macOS is swapping to disk. Quit the heaviest apps, close tabs, and check Swap Used. What swap is · Read your memory numbers
3. Free up disk space
A nearly full disk slows everything: macOS needs free space for swap, caches and updates. As a rule of thumb, keep at least 10–15% free (25–40 GB on a 256 GB Mac). The fastest wins are usually in System Data: Time Machine local snapshots, old iPhone backups, app caches and developer files. Free up space step by step · What's in System Data
4. Trim login items and background apps
Open System Settings › General › Login Items & Extensions. Remove apps from Open at Login that you don't need straight away, and turn off background items you don't recognise or no longer use. Fewer things starting means a faster startup and more free memory.
5. Tame the browser
A single browser with 40 tabs can use more memory than every other app combined. Close what you're not reading, and remove extensions you don't use (each one runs on every page). Safari and Chrome both have a built-in tab memory saver.
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6. Let background jobs finish
After a macOS update or when you connect a big drive, Spotlight re-indexes (mds, mds_stores, mdworker) and Photos analyses your library (photoanalysisd). Both are heavy for a while and then stop. Leave the Mac plugged in and awake for an hour. Mac running hot?
7. Update macOS and your apps
Apple fixes performance bugs in point releases. Open System Settings › General › Software Update. If the update says there isn't enough space, here's how to make room.
8. Run First Aid
Open Disk Utility, select your startup disk, and click First Aid. It checks the file system and fixes errors that can slow the disk down.
9. Try Safe Mode
Safe Mode starts the Mac without third-party login items and extensions. If it's fast in Safe Mode, something you installed is the cause. On Apple silicon: shut down, press and hold the power button until you see startup options, select your disk, then hold Shift and click Continue in Safe Mode. On Intel Macs, hold Shift while it starts.
What doesn't help
"RAM cleaner" and "memory booster" apps free memory that macOS was using as cache, so the Mac has to read it from disk again. Deleting random system files doesn't speed anything up and can stop the Mac from starting. Clearing caches only helps if your disk is nearly full.
Where Tidy Mac fits
Tidy Mac doesn't touch memory or CPU; Activity Monitor is the right tool for those. If a full disk is part of the slowdown, Tidy Mac shows what's filling it, names what's inside System Data, and clears the safe parts to the Trash with Undo.
Frequently asked questions
Why is my Mac so slow all of a sudden?
Usually something new is keeping it busy: an update that triggered Spotlight indexing, a stuck process, a browser tab, or a disk that just crossed into nearly full. Activity Monitor’s CPU tab and Memory Pressure graph show which one in a minute.
Does clearing cache speed up a Mac?
Only if your disk is nearly full. Caches exist to make apps faster, so clearing them on a Mac with plenty of free space makes apps slightly slower until they rebuild.
How much free space should a Mac have?
A good rule of thumb is 10–15% of the disk, and at least 20–30 GB before a macOS update. Below that, swap and updates start to struggle.
Will a factory reset fix a slow Mac?
Sometimes, but try everything above first. A reset is slow, and if the cause was a full disk or too little memory for what you run, it comes back.