Well, that came through my mind also, but something isn't right. Let's see. For much efficiency that intel chips have, 12% usage in ppc, could be like 3 or 4% on intel. And that's not right. With the open .app (without playing) and hidden, activity monitor reports between 0 and 0,3% cpu on intel which cannot translate to 11 to 13% in a 1.5Ghz ppc. An open app with no activity and no background processes shouldn't use any cpu. Isn't this true??
And more; now iTunes is playing and using 9%; less than when not playing!!!