CoreSync is a component of the Creative Cloud desktop app and part of its installation. CoreSync is responsible for syncing data between your machine and Creative Cloud. It syncs all the files in the Creative Cloud Files folder on your machine with Adobe servers. CoreSync also syncs cloud documents created in applications like Adobe XD and Adobe Photoshop.
The CoreSync.exe process should not impact CPU performance when your machine is idle. It may take up some CPU for a few seconds when syncing folders with the Creative Cloud. But if you see continuous high CPU usage by CoreSync.exe, it may be an indication that it is not genuine. See How do I know if CoreSync.exe running on my machine is genuine?
Check if it is located at C:\Program Files (x86)\Adobe\Adobe Sync\CoreSync. If the location is different, you have a non-genuine copy of CoreSync and your data might be compromised. See Non-genuine copy of CoreSync.exe?
There should only be one process running on the Task Manager with the name CoreSync.exe. If you see more than one CoreSync.exe, check the file locations for all of them.
If you have or think you may have a non-genuine copy of CoreSync.exe running on your machine, it is possibly a malicious application that is responsible for the high CPU usage. It should be removed from the machine.
It is recommended that you take the following measures to remove the non-genuine copy of CoreSync and get a genuine copy: