When I adjusted the frame rate to Unlimited, I usually see the word "unlimited" next to the actual FPS.
Now I get this info (circled in yellow) where the "unlimited use to be. Don't know what that info is about.
I'm using an ATI Radon HD 4800 video board.
I did find some info on the customizing Shift+Z
I'm still not sure what the data circled in yellow refers to.