MDS or “metadata server” is a process that you may have seen appear on certain occasions on your activity monitor, activity monitor you have probably visit because your Mac was starting to run slow or was overheating suspiciously.
In fact, if your Mac is running slow or overheating, the mds process may be consuming up to 90% of your CPU resources.
Don’t worry, it’s normal, there’s nothing wrong with your computer.
The root of this behavior lies in Spotlight, Apple’s application launcher (although I recommend much more to use Alfred.
When Spotlight indexes (i.e. searches and lists) all your files so that it can show them to you when you need them, it consumes a significant amount of resources.
You can easily see if Spotlight is indexing your storage drive because when it does, the magnifying glass of Spotlight icon will show a black dot inside it.
In fact if you click on it you will see a progress indicator that shows you an estimate of the time remaining until the process is finished and therefore mds disappears.
This means: You should not kill or terminate the process.
For mds to stop consuming your CPU resources you do not have to do anything else but wait.
This may take some time depending on the size of your storage, if it is an ssd or not, the time that has passed since the last indexing … But usually between 15 and 45min later, you can enjoy your Mac at full capacity.