15 ways to un-slow your Mac — from a 30-second check to a full diagnostic
"My Mac is running slow." It's the single most common complaint, and also the vaguest. The slowness could be a browser with 90 tabs, a runaway process, memory pressure, a full disk — or all of the above at once.
This guide is ordered from the fastest fixes to the deepest diagnostics. Start at the top, and stop when your Mac feels normal again.
Quick wins (under 2 minutes)
1. Restart your Mac
It sounds obvious, but a Mac that's been running for weeks accumulates stale processes, leaked memory, and temporary files that only a restart clears. If you haven't restarted in a while, do it now — it fixes a surprising number of "slow Mac" problems instantly.
2. Close browser tabs
Each tab is a separate process consuming RAM and CPU. A browser with 60+ tabs can easily use 4–8 GB of memory by itself. Close what you're not actively reading.
3. Quit apps you're not using
macOS keeps apps in memory even when minimized. Check your Dock: every app with a dot under it is running. Right-click and quit anything you haven't touched today.
4. Check for macOS updates
Open System Settings → General → Software Update. Some slowdowns are bugs that Apple has already patched. Let the update install and restart.
Activity Monitor checks (5 minutes)
5. Find CPU hogs
Open Activity Monitor (search for it in Spotlight), click the CPU tab, and sort by % CPU descending. If one process is consistently above 100%, it's a problem. Common offenders: browser helper processes, cloud sync apps, and Spotlight indexing (mds_stores).
6. Check memory pressure
Switch to the Memory tab. The chart at the bottom is your key diagnostic: green means fine, yellow means pressure is building, red means your Mac is swapping heavily to disk — which makes everything slow. See our deep dive on memory pressure for what to do when it's red.
7. Look at disk activity
The Disk tab shows read/write rates. If you see sustained high activity with no obvious cause (you're not copying files or running a backup), something is thrashing your disk — often swap or runaway indexing.
Storage and startup (10 minutes)
8. Check free disk space
Click the Apple menu → About This Mac → Storage (or System Settings → General → Storage). When your startup disk is below 10–15% free, macOS struggles to manage virtual memory and temp files, and everything grinds. If you're low, start with clearing System Data.
9. Trim login items
Open System Settings → General → Login Items & Extensions. Every app listed there launches at startup and stays running. Remove anything you don't need immediately at login — cloud apps, helpers, updaters. Each one shaved off is a few hundred MB of RAM and a few percent of CPU freed up.
10. Disable visual effects
Go to System Settings → Accessibility → Display and enable Reduce motion and Reduce transparency. These won't make a fast Mac faster, but on an older machine they reduce the GPU load that WindowServer imposes.
Deeper diagnostics (15–30 minutes)
11. Reset Spotlight index
If mds_stores is using high CPU for hours (not just after an update), the Spotlight index may be corrupted. Go to System Settings → Spotlight → Search Privacy, add your startup disk, wait a moment, then remove it. Spotlight will reindex from scratch — it takes time, but it stops the endless loop.
12. Check for memory-leaking apps
In Activity Monitor's Memory tab, sort by Memory. If an app is using 5+ GB and climbing, it has a memory leak. Quit and reopen it. If it keeps growing, check for updates — the developer likely knows about the leak.
13. Boot in Safe Mode
Restart and hold Shift (Intel) or hold the power button and choose "Safe Mode" (Apple Silicon). Safe Mode disables login items, non-essential extensions, and clears caches. If your Mac is fast in Safe Mode, the problem is a third-party app or extension — not your hardware.
14. Check disk health
Open Disk Utility, select your startup disk, and click First Aid. It checks and repairs file system errors. A corrupted directory structure can cause slowdowns that look like hardware failure but are purely software.
15. Restart NVRAM / full power cycle
On Intel Macs, an NVRAM reset (hold Option+Command+P+R on boot) can clear stale display resolution, startup disk, and kernel panic data. On Apple Silicon, a simple shut down → wait 30 seconds → start up achieves the same effect — there's no separate NVRAM reset procedure.
The pattern: most "slow Mac" problems trace back to three things — too many apps running, not enough free disk space, or one misbehaving process consuming all CPU or memory. Fix those three, and the Mac is almost always fine.
Skip the checklist — just ask
Gigatidy is a conversational AI that diagnoses your Mac in seconds. It checks memory, CPU, disk, startup items, and running processes — then tells you exactly what's slowing things down, in plain English.
Try Gigatidy →FAQ
Why is my Mac so slow all of a sudden?
Sudden slowdowns are usually caused by a single runaway process (check Activity Monitor → CPU tab), a macOS update indexing in the background, or your disk running out of free space. Restart first, then investigate.
Does restarting my Mac actually help with speed?
Yes. A restart clears leaked memory, kills stale processes, and resets temporary files. If your Mac has been running for weeks, a restart alone can recover gigabytes of RAM and normalize CPU usage.
How do I know if my Mac needs more RAM or a new SSD?
Open Activity Monitor and check the Memory Pressure chart. If it's consistently red with plenty of free disk space, you're hitting a RAM limit. If your disk is nearly full and the Mac is slow even after closing apps, storage is the bottleneck. On modern Macs with soldered components, freeing up disk space and reducing open apps is usually more practical than a hardware upgrade.