Microsoft has issued also an optional (revised) update KB3102812 for Windows 8.1 and Windows Server 2015 R2 on 11/4/2015. It fixes some Windows Update problems.
Update KB3102812 Installing and searching for updates is slow and high CPU usage occurs in Windows 8.1 and Windows Server 2012 R2 fixes the following issues:
- When you install updates by using System Center Configuration Manager, the installation takes a long time, and System Center Configuration Manager becomes overloaded.
The Svchost.exe process occupies 100 percent of CPU usage when you upgrade a Windows Update client to Windows 10.
The update is distributed as optional via Windows Update, but may also be downloaded and installed manually. In case you need to block the Windows 10 upgrade, use the tool discussed in my blog post Block Windows 10 Upgrade using GWX Control Panel.