Just got back from traveling, so I wasn't able to see this before, but thanks so much for the feedback and info! Also enjoyed your YouTube video for the game.
Hi, further update. Since last playing I've upgrade the iMac from an Intel Core 2 Duo 2.0Ghz to an Intel Extreme Core 2 Duo 2.8 (model X7900 to be exact) which is the fastest, most modern CPU the iMac 7,1 can support, and I ran you game again on max settings. Flawless. No fps dip even during the horror glitches later in songs. So I feel the game is more CPU intensive than GPU.
Just thought to let you know if in case in future updates you want to put in system requirements. :)