If yoy did that thing Nus suggested ("Try stopping the store apps from being allowed to run in the background. Go to: Settings->Privacy->Background Apps ) , then after the change in the registry I suggested you can Undo that Settings->Privacy->Background Apps change and Live tiles will work again.
If not and there is another problem I dont't know the solution
Just turn off 'Show me tips about windows'
Setting - System - Notifications and actions
My CPU usage dropped immediately from 30% to 0%
Whatever the problem was it stopped. I think other people had the problem and microsoft sent an update
Here's a quote from another thread that might shed some light:
Quote Originally Posted by Mystere View Post
As you can see from this article:
What is RuntimeBroker.exe and Why is it Running?
Runtime broker is part of the security subsystem of Universal Apps (then called Metro apps). Essentially, all access to files and other resources goes through the Runtime broker.. so what this means is that it's only accessing files on the behalf of another Universal app. This is probably something like the Photos app or something that searches through indexed files and catalogs them, or indexes them.
You should use something like FileMonitor to see what it's actually accessing if you're interested.
Quote