XPS 9370 performance issue

Hi,

we bought the XPS 9370 a week ago with Ubuntu installed. Then we installed Windows 10 x64 Enterprise and connected the monitor Benq GW2765 (2K resolution) over Dell TB16 Dock Station. After 20 minutes of the work (Windows 10 x64, Chrome, Outlook, Excel) any applications don't respond to user actions. When it comes back I try to work with Outlook and I see, if I just scroll an email then CPU and GPU are very loaded. Please look at the pictures:

What is going on? Why it takes so much CPU and GPU performance? How can I fix it or should I return the laptop back to a store as not suitable for our purposes?

Thank you in advance!