I put Yosemite on a retina MBP which is my secondary machine. It is very slow, even DP2. On Mavericks it was lightning fast. I have it on a secondary partition so I can revert back to Mavericks if necessary but I really wanted to start practice developing swift apps for OS X. Even when the only software I have running is system preferences, I get the spinning beach ball when I click on any option in system preferences. Does anyone else have this same issue with the beta? Any potential suggestions? I 100% expected an issue like this to happen and I can revert back to Mavericks easily, but before I did I was wondering if any of you had found a solution. EDIT: fixed. It was a program called "Parallels Access" causing the issue!