Immediate answer: what to do first when your Mac is running slow after update

If your Mac is running slow after update, don’t panic. Many slowdowns are temporary: Spotlight is indexing, background updates or migrations are finishing, or caches are rebuilding. Give the Mac a little time (30–60 minutes) while it’s idle and plugged in.

While waiting, open Activity Monitor and sort by CPU and Energy to spot runaway processes. Quit or force-quit apps that peg CPU or memory. Also check Storage in About This Mac — low free space (under ~10–20%) is one of the most common causes of sluggish performance and slow boot.

If the slowdown persists after an hour, boot into Safe Mode to see if performance improves. Safe Mode prevents third-party kernel extensions and login items from running; if the Mac is faster in Safe Mode, a login item or kernel extension is likely the culprit.

Why a Mac can become slow after an update

macOS updates change system behavior: Spotlight can reindex your entire drive, background daemons may launch to migrate settings, and third-party kernel extensions or drivers might be incompatible. These processes can consume CPU, I/O, and memory, producing a noticeable slowdown.

Storage pressure causes virtual memory to swap to disk more often. If your SSD or HDD is nearly full, or if a failing drive has poor I/O, apps will respond slowly and rebooting will take longer. Even seemingly small things like corrupted caches or a bloated login item list add tens of seconds to boot time and reduce interactive responsiveness.

Hardware limits also matter: older Macs, especially those with HDDs, limited RAM, or aging batteries, will struggle with modern macOS releases designed for faster NVMe SSDs and more RAM. Software updates can increase baseline resource requirements and expose hardware bottlenecks.

Immediate fixes you can do right now (safe and reversible)

First, check Activity Monitor (Applications → Utilities → Activity Monitor): sort by CPU and Memory. Identify apps using excessive resources and quit them. If a process is misbehaving, select it and click the stop icon to force quit. This often restores snappy responsiveness quickly.

Second, free up disk space. Remove large unused files, empty the Trash, and use About This Mac → Storage → Manage to enable storage optimization. Aim to keep at least 10–20% free. When storage is tight, macOS cannot swap efficiently and Spotlight or Time Machine local snapshots can consume space.

Third, restart in Safe Mode (hold Shift at boot for Intel; for Apple Silicon, hold the power button and choose Safe Mode). Safe Mode disables login items and third-party extensions; if your Mac runs faster, review and remove suspicious login items (System Settings → Users & Groups → Login Items) and uninstall problematic apps.

How to speed up boot times and fix slow boot on Mac

Start with login items: unnecessary apps that open automatically can significantly delay the desktop. Open System Settings → Users & Groups → Login Items and remove anything not required. For older macOS versions, the path may be System Preferences → Users & Groups.

Reset NVRAM/PRAM and SMC (Intel Macs) or use Apple Diagnostics for deeper hardware checks. Resetting NVRAM can clear misconfigured boot settings and SMC reset addresses power and thermal management oddities. For Apple Silicon Macs, shut down and wait 30 seconds, then power on again — SMC-type functions are managed by the chip automatically.

Run Disk Utility → First Aid on your startup disk to repair directory issues. If First Aid reports errors it can’t fix, consider booting into Recovery (Command-R) and reinstalling macOS without erasing data. Reinstalling refreshes system files and often fixes stubborn slow boot problems caused by corrupted system components.

Advanced troubleshooting: diagnostics and recovery

If the basic steps don’t help, deeper diagnostics are necessary. Run Apple Diagnostics (restart and hold D on Intel; for Apple Silicon, shut down, then press and hold the power button until options appear, then choose diagnostics). The tool checks hardware like memory and SSDs for faults that cause slowdowns.

Check system logs for repeated errors: open Console and filter for faults or repeated crashes. Kernel panics or recurring launcher failures often indicate a driver or kext problem. Uninstall or update the software that appears in logs; kernel extensions should be updated or removed if they’re incompatible with the current macOS release.

For power-users, safe clean installs or target-disk backups can eliminate software-level causes. Back up with Time Machine or clone your drive with Carbon Copy Cloner, then reinstall macOS. If performance is restored on a clean system, migrate user data selectively to avoid reintroducing the issue.

Tools and utilities that help (and how to use them safely)

Apple’s built-in tools are usually enough: Activity Monitor, Disk Utility, and Storage Management. Use them first. For advanced cache and permission repairs, OnyX (a free macOS utility) is widely used — download from the official developer site and ensure the version matches your macOS release.

Monitoring tools like iStat Menus reveal temperatures, CPU throttling, and I/O bottlenecks. If you see frequent thermal throttling, clean vents and fans or check for aging batteries that reduce turbo performance. High sustained temperatures force the CPU to slow down and will make a Mac feel sluggish.

Be cautious with “speed booster” apps that promise dramatic results. Prefer lightweight, reputable utilities and always back up before making system-level changes. If an application asks for root access to remove system files or kernel extensions, verify its trustworthiness first.

Preventive maintenance to keep your Mac fast

Keep macOS and apps updated — security and performance improvements arrive regularly. However, read release notes and, after major OS upgrades, monitor forums for reports of incompatibilities if you rely on older third-party tools.

Keep at least 10–20% of your drive free, enable automatic storage optimization where appropriate, and maintain a regular backup schedule with Time Machine. Regular backups let you experiment safely and restore quickly if an update causes issues.

Periodically review Login Items and launch agents. Uninstall unused apps and remove leftover preference files. For older Macs, consider upgrading to an SSD or adding RAM (if the model supports it) to gain the most noticeable performance improvement.

Common commands and short tips (copy-paste safe)

To rebuild the Spotlight index (if Spotlight indexing is hogging resources):

sudo mdutil -E /

To view login items and launch agents, check these folders for third-party files that may slow boot:

• /Library/LaunchAgents and /Library/LaunchDaemons
• ~/Library/LaunchAgents

Use these directories cautiously: remove only items you recognize. For a reversible step, move suspect files to a backup folder on your Desktop and reboot to test effects.

FAQ — three most common user questions

Why is my Mac so slow after an update?

Updates trigger reindexing, cache rebuilds, and background migrations, which can temporarily use CPU, memory and disk I/O. If slowness persists beyond an hour or two, check Activity Monitor, free disk space, boot in Safe Mode to isolate issues, and run Disk Utility → First Aid to repair file system issues.

How do I fix slow boot on my Mac?

Remove unnecessary Login Items, reset NVRAM/SMC if using an Intel Mac, run First Aid in Disk Utility, and check for failing peripherals or disks. If those steps fail, reinstall macOS from Recovery after backing up your data.

How can I speed up my MacBook without losing data?

Clean caches and temporary files, uninstall unused apps, empty Trash, and enable storage optimization. Run Activity Monitor to stop resource-hungry apps. Always back up first (Time Machine or a clone) before any major cleanup or reinstall.