I was experiencing consistent high CPU usage in Windows 8 Pro x64. The cause was svchost running at a constant 25% CPU, even at idle. I checked the services that the svchost was running, and toggled them on/off until I found the cause.
It turns out one service, IPHLPSVC (IP Helper), was responsible for all the CPU usage. Once I stopped the service, the CPU dropped down to 0-1% at idle.
I did some research and it seems like IPHLPSV is for transition to IPv6. I'm still on IPv4 and don't experience any issues with the task stopped. Should I just disable the task? Does anyone have any ideas of what could be causing the issue?