Recently Josh from B Kuhl Entertainment came in to the shop with his DJM-900SRT, 2 CDJ-2000NXS (Thanks for the business) and a newer Mac Book Pro. His audio files played fine but the visual feedback was choppy. We checked his activity monitor, and found Serato was using over 100% of the CPU. Because we have experienced problems with iTunes intergration into Serato in the past, we found success when we removed the cursor from the iTunes crate. We then went into Serato setup, choose the Libary + Display tab, we then unchecked the Show iTunes Libary box. This lead to the visual feedback playing back smoothly, even with 4 decks playing simultaneously.