I have recently experienced a high CPU usage of Modern Setup Host on my Windows 10. It seems most of the issues with this application are regarding upgrades from Windows 8, but I have already done this some months ago. The problem started somewhat a week ago, though. If I restart my computer, it is fine for certain amount of time, but afterwards it starts again. What could be the issue? 🙂

Thanks for posting your query on Microsoft Community.

We understand the inconvenience caused and we will try our best to resolve the issue.

To assist you better, please provide few details.

1) Did you make any changes to the computer, prior to the issue?

2) What is the make and model of your computer?

This issue might occur due to any third party application conflict.

I suggest you to preform clean boot and check if it helps.

A clean boot is performed to start Windows by using a minimal set of drivers and startup programs. This helps eliminate software conflicts that occur when you install a program.

Refer to the below link:

Note: Steps mentioned for Windows 8/8.1, will work fine with Windows 10.

Disclaimer: Please go through the section: How to reset the computer to start as usual after troubleshooting with clean boot of the Kb article to boot the computer in normal startup after fixing the issue.