A Mac that used to feel snappy and now feels sluggish almost always has a software explanation. Apple Silicon Macs (M1 through M4) are efficient enough that genuine hardware bottlenecks are rare for most workloads. The causes are almost always a runaway background process, a full disk, or login item bloat. Here is how to find and fix each one.
What changed in 2026
- Apple Silicon M3 and M4 Macs have unified memory architectures that handle RAM pressure better than Intel, but they still slow down when storage is near-full because macOS uses the SSD as overflow memory.
- macOS Sequoia and later moved more settings into System Settings (the redesigned System Preferences) — screenshots in older guides are outdated.
- Background AI features (live text, semantic photo indexing, Spotlight ML) run after major updates and temporarily spike CPU and disk usage. This usually resolves in 30–60 minutes.
- Third-party cleaner apps are still widely advertised but Apple's own storage tools have caught up; you rarely need paid third-party utilities.
Step 1: Check Activity Monitor first
Before changing anything, open Activity Monitor (Spotlight → Activity Monitor) and check:
- CPU tab: Sort by % CPU descending. Anything above 30–50 % sustained is suspicious unless it's a render or compile task.
- Memory tab: Check "Memory Pressure" at the bottom. Green = fine. Yellow = watch it. Red = you need more RAM or less open apps.
- Disk tab: Watch for sustained high reads/writes with a process name you do not recognize.
Note the process name before killing it — some background processes restart immediately if you force-quit without disabling them first.
Step 2: Trim login items and background agents
- System Settings → General → Login Items & Extensions.
- Under Open at Login, remove anything you do not need at startup.
- Under Allow in Background, review and disable agents from apps you rarely use — these run silently and consume CPU/memory.
Common candidates: Dropbox, OneDrive, Google Drive (if you use another sync service), Microsoft AutoUpdate, Creative Cloud Desktop, Zoom Scheduler, Adobe updaters.
Step 3: Free up startup disk space
macOS becomes significantly slower when the startup disk is under 10–15 GB free. Sequoia and later need space for virtual memory swap, Time Machine local snapshots, and system operations.
- System Settings → General → Storage — click the info button on each category for cleanup suggestions.
- Large files: Use the built-in Storage recommendations → Review Files, or Finder → All My Files sorted by size.
- iCloud Desktop & Documents — enable to offload files to iCloud and free local space.
- Empty Trash — obvious but frequently overlooked.
Aim for at least 20 GB free; 50+ GB free is comfortable.
Step 4: Let post-update indexing finish
After a macOS update, mds_stores (Spotlight indexing), photoanalysisd (Photos AI), and cloudd (iCloud sync) spike for 30–90 minutes. This is normal. If Activity Monitor shows these processes, wait before doing anything else — they will stop on their own.
If mds_stores has been high for more than a few hours, you can reindex:
sudo mdutil -E /
This deletes and rebuilds the Spotlight index. Expect 30–60 minutes of indexing after running it.
Step 5: Check for memory pressure and swap usage
Open Activity Monitor → Memory tab → bottom bar:
- Swap Used: > 0 means macOS is using the SSD as overflow RAM. Any swap on an Apple Silicon Mac means you have run out of unified memory for current workloads.
- If swap is consistently above 1–2 GB, close background apps or consider moving to a Mac with more unified memory.
| Symptom |
Likely cause |
Fix |
| Slow boot |
Login item bloat |
Clear Login Items |
| Sluggish all the time |
Disk nearly full |
Free 20+ GB on startup disk |
| Fan noise, hot |
Runaway process |
Activity Monitor → force-quit offender |
| Slow after update |
Background indexing |
Wait 30–90 min or reindex |
| App launch delay |
Low RAM / high swap |
Close background apps; reduce open tabs |
Common mistakes
Deleting system caches manually. macOS manages its own cache invalidation. Deleting them manually causes apps to rebuild caches (making things temporarily slower) with no long-term benefit.
Ignoring the "Allow in Background" list. These background agents are newer than the traditional Login Items list and are frequently populated by app installs without clear disclosure.
Running CleanMyMac or similar subscription tools for cache cleaning. These are largely unnecessary on modern macOS and the subscription cost rarely delivers real value.
Dismissing a runaway process too quickly. If you force-quit a background agent that restarts automatically, you have fixed nothing. Disable it in Login Items or uninstall the app.
What to skip
- Manual plist editing to disable system services — this breaks system integrity checks and causes problems after updates.
- Third-party RAM-clearing apps — they evict useful cached data from RAM and make the next app launch slower, not faster.
- Reinstalling macOS as a first step — almost every slow-Mac problem is fixable without reinstalling.
FAQ
Why did my Mac slow down after a macOS update?
Post-update background tasks (reindexing, iCloud sync, photo analysis) run for 30–90 minutes. Let them finish before troubleshooting further.
Do Macs need antivirus software?
macOS has built-in malware protection (XProtect, Gatekeeper). A reputable third-party scanner is reasonable if you handle sensitive files, but it adds CPU overhead. Do not run more than one scanner.
How much free space does a Mac need to run well?
Keep at least 20 GB free on the startup disk. For a 256 GB Mac, that means keeping usage under ~230 GB.
Will adding more RAM speed up my Mac?
On Apple Silicon, unified memory is shared between CPU and GPU. If you see sustained red memory pressure or consistent swap usage, more RAM will help. If memory pressure is green, RAM is not the bottleneck.
Where to go next
See How to free up iPhone storage in 2026, How to improve laptop battery life in 2026, and How to fix overheating laptop in 2026.