I'm not quite sure how this works, but right now, I'm ripping all of my CDs before I put them in storage, and I've got a 2011 iMac, PowerBook G4 12" and 1st-gen eMac (700Mhz) all ripping at them. For some reason, the eMac registers the highest ripping speed, consistently above 10X while the other two average around 9X or slightly over.
Either way, I feel productive.
Either way, I feel productive.