I posted the brainstorm idea because I want it to be clear across the whole system that the CPU is under heavy load and that's why the UI isn't "working". Fading the app causing the problem isn't good enough; it may be hidden in the background.

I agree that the throbber isn't ideal, but I couldn't think of something better.

A "Brainstorm" is supposed to be about people throwing out all sorts of ideas, so keep 'em coming!

How would you show to a user that they need to be patient for a minute, no matter what app they were in?