Aghhh~ I had this problem so much!
The CPU at 100% is a common problem with most fresh instals of windows 8 or higher, at least I got that with each fresh instal.
My trick to fix these problems was the following
Open Task Manager - Services - Open Services - Find the following services (I will post them bellow) - Propriete - Start up - Disabled
''Background Inteligence Transfere Service
''Superfetch
These 2 are the main ones but I also turn Windows Search and Windows Update to Manual sometimes.
After you do what I told you, just Restart your device - Open Task Manager - Services - Open Services again and check that the Services are now on Disabled.
Hope this helped, it always helped me with the CPU 99% problem.