You open Activity Monitor because your Mac is hot, the fans are loud, and the battery is dropping, and at the top of the CPU list you find a strange process called mds_stores. This is a very common sight after a macOS update. mds_stores high CPU usually means Spotlight is indexing your files, and in most cases it stops by itself. This guide explains what mds_stores is, how long it should run, when it is a real problem, and how to fix it step by step without breaking anything.
What are mds, mds_stores and mdworker?
These are background processes that belong to Spotlight, the search feature on your Mac. Spotlight builds an index of your files, apps, emails and other data, so that when you press Command + Space and type a word, results appear instantly.
- mds is the main metadata server process.
- mds_stores manages the stored index data.
- mdworker (sometimes shown as mdworker_shared) reads individual files and adds them to the index.
They are safe, genuine parts of macOS, not malware. Do not try to delete them. If you want to be sure, you can check in Activity Monitor that the processes belong to the user “root” or your account, and that their names are spelled exactly as above.
Why does mds_stores use so much CPU after an update?
After a major macOS update, the Spotlight index may need to be rebuilt or updated so that it works with the new version. During that time, the Mac reads a large number of files, so CPU use and heat go up. This is especially noticeable when you have:
- A large number of files, photos or documents.
- Big mail libraries.
- External drives connected to the Mac.
- Cloud folders that sync many files.
- A nearly full drive, which slows down all disk work.
Because this work is normal, the first rule is to give the Mac time.
How long should it take?
There is no exact number, because it depends on the amount of data, the speed of your drive and whether you are using the Mac while it works. For many people, indexing finishes within a few hours. For big libraries, it can take a day or two. If the CPU use is still high after several days with the Mac plugged in and mostly idle, it is worth investigating.
How to confirm Spotlight is the cause
- Press Command + Space, type Activity Monitor, and press Return.
- Click the CPU tab and sort by % CPU.
- Look for mds_stores, mds or mdworker at the top.
- Click the Energy tab to see whether they use a lot of power.
You can also click the Spotlight search field and type something. If Spotlight shows a message saying that it is indexing, then that explains the activity.
Fixes for mds_stores high CPU
Fix 1: Wait, plug in and leave the Mac alone
Connect the Mac to power, close big apps and let it sit with the lid open for a few hours, or overnight. Many cases end here. If you want to know how this affects battery life in general, read our guide to macOS 27 battery drain.
Fix 2: Restart the Mac
Click the Apple menu and choose Restart. A restart can clear a stuck process and let indexing continue properly.
Fix 3: Free up storage
When a drive is almost full, indexing slows down and temporary files cannot be created. Follow our guide on how to free up storage on Mac and aim to keep at least 10 to 15 percent free.
Fix 4: Exclude folders and drives from Spotlight
If you have folders that do not need to be searchable, such as big archives, virtual machine files, backup drives or download folders, you can tell Spotlight to skip them.
- Open System Settings and click Spotlight.
- Click Search Privacy.
- Click the plus (+) button and add the folder or drive.
- Click Done.
Spotlight will no longer index those items. You can remove them from the list later if you change your mind.
Fix 5: Rebuild the Spotlight index
If indexing seems stuck or search results are wrong, rebuilding the index often solves it. There are two ways.
Method A: Use Search Privacy
- Open System Settings > Spotlight > Search Privacy.
- Add your main drive (usually Macintosh HD) to the list.
- Wait a few seconds, then remove it with the minus (-) button.
- Spotlight starts re-indexing from scratch. Expect high CPU use for a while.
Method B: Use Terminal
Open Terminal and enter this command to erase and rebuild the index for your main drive:
sudo mdutil -E /
Type your Mac password when asked (nothing appears as you type). You can check the status with mdutil -s /. Only use Terminal commands you understand, and expect another round of indexing afterward.
Fix 6: Disconnect external drives
Unplug external drives, memory cards and disk images for a day. If CPU use drops, the drive was being indexed. Add it to the Search Privacy list if you do not need to search it.
Fix 7: Update your apps and macOS
Open System Settings > General > Software Update and install any updates. Also update apps that use Spotlight data, such as email and note-taking apps, and cloud-storage apps. Bugs in earlier versions are often fixed in point releases. If you cannot see the update, read why you may be unable to update to macOS 27.
Fix 8: Check for runaway apps
If mds_stores is only one of many busy processes, the real cause may be another app. Select a heavy app in Activity Monitor and quit it. If it will not close, use force quit.
Which fix for which situation?
| Situation | Try this |
|---|---|
| Just updated macOS, Mac is warm | Plug in and wait several hours |
| Still busy after a day | Restart and free up storage |
| Large external drive connected | Disconnect or exclude it |
| Search results are missing or wrong | Rebuild the index |
| Everything is slow, not just mds | Check other processes and your storage |
Should you turn off Spotlight completely?
You can disable indexing with Terminal, but it is not recommended for most people. It breaks Spotlight search and other features that depend on it, such as finding apps and files quickly, and it can confuse some apps. If you need to stop indexing temporarily, it is safer to exclude large folders using Search Privacy instead.
When mds_stores may signal a bigger problem
- High CPU use that continues for many days with the Mac idle.
- The index keeps restarting after every reboot.
- Your Mac becomes slow, hot or noisy even after you rebuild the index.
- Disk errors or messages about a damaged volume.
In these cases, back up your files first with Time Machine, then open Disk Utility and run First Aid on your startup disk. If the problem continues, contact Apple Support. Your Mac may also be generally sluggish for other reasons; our article on a Mac running slow after an update lists more fixes.
How to avoid Spotlight problems in the future
- Keep your drive from filling up, so that the system has room to work.
- Exclude big archives, virtual machine files and backup drives in Search Privacy.
- Install updates when you can leave the Mac plugged in and idle for a while afterward.
- Keep your apps updated, since search and mail apps use Spotlight data.
- Restart the Mac now and then, rather than leaving it running for weeks.
If you are not sure whether the problem started with the update or earlier, note the time when you first noticed the heat. Compare it with the date you installed the update. If the symptoms began right after installation, indexing is by far the most likely cause. If they started days earlier, look at other apps in Activity Monitor and check whether a new external drive or cloud folder was added around the same time.
Frequently Asked Questions
What is mds_stores on Mac?
It is a Spotlight process that manages the search index. It is a normal part of macOS.
Is mds_stores a virus?
No. The genuine process is part of Spotlight. High CPU use usually means indexing, not malware.
Why is mds_stores using so much CPU?
Spotlight is probably indexing your files after an update, a large file change or a connected drive. It normally finishes on its own.
How long does Spotlight indexing take?
From a few hours to a day or two, depending on how much data you have and how busy the Mac is.
Can I kill mds_stores?
You can quit it from Activity Monitor, but macOS will start it again. It is better to fix the cause by waiting, restarting, freeing space or rebuilding the index.
Conclusion
High CPU use from mds_stores is nearly always Spotlight rebuilding its index, especially after a macOS update. Give your Mac time while it is plugged in, restart it, free up storage, and exclude folders and drives you do not need. If search looks broken or indexing never finishes, rebuild the index in Search Privacy or with Terminal. Keep a backup in case a disk problem turns up, and contact Apple Support if the Mac stays hot and slow after all of this.
