Keep in mind that it's going to use more CPU than necessary because he isn't doing delta timing, opting instead to sleep and cap the FPS <.<
Well he's half-way there as I understand it...For each iteration you time how long it takes, calculate how much of the 1/xth of a second you have left, and release the CPU for that amount of time. And you also use Delta-timing in order to ensure objects move at the same rate even if the FPS drops below x updates per second.
At least that's how I do things. It means you're using exactly how much CPU you need to use, and if the person's still getting the entire CPU swallowed then you definitely have some performance issues to work out or they have a computer that just can't handle it.
You know, the need to release the cpu is really something books and online tutorials need to
actually start mentioning -_- I barely ever see it mentioned except on forums when people are commenting on a person's program
Kudos for, seemingly, actually doing it ^.^
Anyway, I ran the game with only minor 'flickering' graphical issues, that image 'tearing' you mentioned. It used like 2% of the CPU at most and I could close it fine ^^