Mac Slow After the macOS 27 Update? What's Normal

Written for macOS 27 Golden Gate and macOS 26 Tahoe.

Apple released macOS 27 Golden Gate on September 14, 2026. After the upgrade, a lot of people notice the same thing. Apps take a beat longer to open, the Mac is warm while you're doing nothing, and the battery drops faster than it used to. Most of the time that's the Mac catching up on work the upgrade created, and it passes. This guide explains what's normal, how long it lasts, and what to check when it doesn't settle.

#Key takeaways

• A slow first day or two is common. Spotlight, Photos and other system tasks redo their work after a major upgrade.
• Help it finish. Keep the Mac plugged in, awake and online, then restart once.
• Install macOS 27.0.1 or later. Apple shipped it on September 28, 2026.
• If it's still slow after a few days, check CPU, memory pressure, free disk space, login items and old apps, in that order.
• Don't reach for a reinstall or a downgrade first. Most causes are much simpler.

#Why does a Mac feel slow right after a major update?

Because it's busy with work you can't see. Several system tasks start over after a major upgrade, all at the same time:

• Spotlight re-indexing. Apple says Spotlight indexes after you install a software update or upgrade, and that it "can take hours or even days" depending on how much data you have. You'll see mds_stores and mdworker in Activity Monitor. Our Spotlight indexing guide covers this in detail.
• Photos analysis. The Photos library is analyzed again in the background. In Activity Monitor this usually shows up as photoanalysisd or mediaanalysisd.
• System assets. Apple says Apple Intelligence is automatically available on eligible devices when you update to the 27.0 releases, and it lists up to 14 GB of on-device storage for it on some Macs. Getting those models and other on-demand assets in place is more background work.
• Syncing and app updates. iCloud, mail accounts and apps catch up after the restart, and many apps update themselves for the new system.

None of this is a fault, but it all competes for the processor, memory and disk with the apps you're using, so the Mac feels slower until it's done. The same work also takes up disk space for a while, which we cover in lost storage after the macOS 27 update.

#How long is "normal" after updating?

Apple doesn't publish a single number, but its Spotlight guidance gives a good sense of scale: hours to days for the first indexing, much faster afterwards. Here's what to expect in practice:

#What should I check first?

Work through these in order. Each check takes a minute or two, and the list starts with the most common causes.

1. Leave it on power overnight. Apple says indexing goes faster when the device isn't in use, is connected to power, and is online. Plug in, keep the Mac awake and on Wi-Fi or Ethernet, and let it work.
2. Restart. This clears temporary files and any background process that got stuck during the upgrade.
3. Install updates. Open System Settings › General › Software Update and install macOS 27.0.1 or later. Then update your apps, from the App Store's Updates section and from each app's own updater.
4. Look at the CPU. Open Activity Monitor (Applications › Utilities), click CPU, and sort by % CPU. At the bottom, Apple's guide explains that System is CPU used by macOS processes and User is CPU used by the apps you opened. High System use after an update usually means indexing or setup work.
5. Check memory pressure. Click the Memory tab and look at the Memory Pressure graph at the bottom. Apple says it's based on free memory, swap rate, wired memory and file cached memory. If it stays high, or Swap Used keeps growing, an app may need more memory than your Mac has easily available. Quit apps you're not using.
6. Check free disk space. Apple's guide for a slow Mac starts with this: the startup disk "may not have enough free disk space." Open System Settings › General › Storage to see where you stand.
7. Review login items. Open System Settings › General › Login Items & Extensions. Remove apps from Open at Login that you don't need, and turn off background items you don't recognize. Our guide on login items and background apps explains what each section means.
8. Find old Intel apps. Choose Apple menu › System Settings › General › About, then click System Report. Under Software › Applications, the Kind column shows Apple Silicon, Universal, Intel or iOS for each app. Intel apps run through Rosetta 2, and Apple has said that Rosetta 2 support for apps ends after macOS 27. Look for native updates now.

If you're comfortable in Terminal, these read-only commands give you the same picture in a few seconds:

# Top 10 processes by CPU; the second sample has the real numbers
top -l 2 -o cpu -n 10 -stats pid,command,cpu | tail -11

# How much swap is in use
sysctl vm.swapusage

# Free space on the startup disk
df -h /

We ran all three on a Mac running macOS 26 Tahoe to check the syntax. top needs two samples because the first one shows no CPU use.

#Is it the update, or something else?

If the Mac is still slow after a week, the update is probably no longer the cause. Use this table to narrow it down:

#Test in safe mode

Safe mode is a clean way to tell macOS problems from third-party ones. Apple says it prevents certain software from loading at startup, including login items and extensions that aren't required by macOS.

On a Mac with Apple silicon: shut down, then press and hold the power button until Loading startup options appears. Select your startup disk, press and hold Shift, click Continue in Safe Mode, and release Shift. You'll see Safe Boot in the menu bar at the login window. To leave, restart normally.

If the Mac feels fine in safe mode, something you installed is the likely cause. Go back through your login items and background items one at a time.

#When to reinstall or contact Apple

If nothing above helps, Apple's guide on reinstalling macOS says it "doesn't remove your apps or personal data", though you should still make a backup first. Contact Apple Support if the Mac is slow even in safe mode, if Disk Utility reports errors it can't repair, or if apps freeze across the board.

#What not to do

• Don't judge speed in the first hours. The Mac is doing a lot of one-time work.
• Don't force quit system processes like mds_stores or photoanalysisd. They'll restart and pick up the work again.
• Don't turn off Spotlight entirely to get speed back. You lose search, and the CPU use was temporary anyway.
• Don't install several cleanup or "speed booster" apps at once. Each one adds its own background helpers.
• Don't downgrade on day one. Going back to macOS 26 Tahoe means erasing and restoring from a backup. Give it a week first.
• Don't delete system folders because a forum post blames them for the slowness.

#Keeping an eye on it afterwards

After the first week, a quick look now and then tells you whether the Mac has really settled. Any monitor that shows live CPU and memory in the menu bar will do, as long as it's light and doesn't phone home.

Freshist has a menu bar HUD with live CPU, GPU and memory readings, and a Status view that lists the processes using the most CPU, power and memory, so a runaway app stands out. When you're freeing disk space, its Analyze treemap shows which folders are big, and its cleaner moves files to the Trash rather than deleting them. See the help docs, how it compares or pricing.

#Related guides

• Spotlight indexing high CPU on Mac: mds_stores explained
• Lost storage after the macOS 27 update? Here's why
• MacBook fan loud or running hot? What's normal
• Login items and background apps on Mac
• How to completely uninstall apps on Mac

#Sources

• Apple Mac User Guide: If your Mac runs slowly
• Apple Support: About Spotlight indexing and search results on Apple devices
• Apple Activity Monitor User Guide: View CPU activity in Activity Monitor on Mac
• Apple Activity Monitor User Guide: View memory usage in Activity Monitor on Mac
• Apple Mac User Guide: Change Login Items & Extensions settings on Mac
• Apple Support: Start up your Mac in safe mode
• Apple Support: How to reinstall macOS
• Apple Support: Reset the SMC of your Mac
• Apple Support: About Power Modes on your Mac
• Apple Support: How to get Apple Intelligence
• MacRumors: Apple releases macOS Golden Gate 27.0.1 with bug fixes
• MacRumors: macOS Tahoe 26.4 displays warnings for apps that won't work after Rosetta 2 support ends