What Is mds_stores and Why Is It Using CPU?

You open your Mac, and immediately the fans start spinning loudly. The system feels slightly sluggish. You open Activity Monitor to see what is going on, and there is a bizarrely named process called mds_stores sitting at the top of the list, using a huge chunk of your CPU.

What exactly is mds_stores, and why is it slowing down your machine?

Here is a simple breakdown of what this process does and why you usually just need to leave it alone.

Spotlight and Metadata Server

mds_stores stands for Metadata Server Stores. It is a core part of Spotlight, the built-in search feature on your Mac.

Whenever you press Cmd + Space to search for a document, an email, or a setting, Spotlight delivers the results instantly. It can do this because it maintains a massive, highly organized database (an index) of every single file on your hard drive.

The mds_stores process is responsible for building and maintaining that index database.

Why is it using so much CPU?

Building a database of millions of files requires a lot of processing power. If you see mds_stores using high CPU, it means Spotlight is actively scanning your hard drive to log new files.

This massive scanning operation typically happens in a few specific scenarios:

• You just bought a new Mac: When you migrate data to a new computer, Spotlight has to read every single file from scratch to build its first index.
• You just updated macOS: Major system updates often require Spotlight to rebuild its database to support new features.
• You transferred a large amount of files: If you just dumped 500GB of photos from an external drive onto your Mac, mds_stores will immediately wake up and start categorizing them.

During this time, the heavy CPU load will generate heat, which will cause your fans to spin up. This is entirely normal. You can read more about thermal management in our guide on Why is my Mac overheating?.

How to Fix mds_stores High CPU Usage

The best and most reliable fix is to do absolutely nothing.

Indexing takes time. Depending on the speed of your hard drive and the amount of data you have, the process can take anywhere from twenty minutes to a few hours. Once mds_stores finishes building its database, the process will quietly go back to sleep, your CPU usage will drop, and your fans will stop spinning.

What if it gets stuck?

In rare cases, mds_stores encounters a corrupt file and gets stuck in an infinite loop. If it has been running at high CPU for multiple days, you can force Spotlight to rebuild its index from scratch.

1. Open System Settings > Siri & Spotlight.
2. Scroll to the bottom and click Spotlight Privacy.
3. Click the + button and select your entire Macintosh HD hard drive to add it to the privacy list.
4. Click Done.
5. Wait a few seconds, then open the Privacy list again, select your hard drive, and click the - button to remove it.

This forces macOS to delete the old corrupted database and start fresh.

Stop Googling Process Names

mds_stores is just one example of the confusing, cryptic process names that macOS uses. When you use Activity Monitor, you are constantly forced to search the web to figure out if a process is safe or dangerous.

We built MacStats to put an end to this guessing game.

MacStats is a menu bar app that tracks your system resources. When you see a spike, you do not have to Google anything. Just click the process in the MacStats menu and use the AI Process Explainer.

MacStats will give you a plain English summary of exactly what the process is doing, like telling you that mds_stores is just updating your search index.

Don't let Spotlight indexing kill your battery. Download MacStats for Free and track mds_stores directly from your menu bar.