I have a Mac Boock pro Retina 13¨ end 2013 top of line (i7 2,8 GHz, 500G SSD PCI, (8G DDR3 1600 MHz), and with a wacom into pend an touch, and the game is imposible to play, is full of lag. But in a iMac medium size early 2009 or 2008 (i5 or i3, 8G kingston DDR3, 350 G HDD), i not remember now, it work perfect, and with the same wacom, but with old osu.
Edit:
ok, i try in a hackinthos with a i7-5960X 3,5 GHz, HyperX Predator (4x8G) 32G DDR4 2133 MHz, 2x GTX 780 DCII OC, booting in a seagate barracuda 1T 7200 rpm and it was the same results tan the mac book.
but in a windows 7 ultimate x64 with i7-5960X oc 5,2GHz, HyperX Predator 32G DDR4 3000 MHz, 2x GTX 780 DCII OC, booting in a HyperX 3K SSD 120G, but osu in a seagate barracuda 3T 7200 rpm it work perfect