I am having the same problem. I am using PR CC and the playback is freezing multiple times per hour. I can quickly save and then force quit (crash) the app. I have tried saving off a new project (new name) and cleaned the caches.
I am searching for answers as well.
iMac 3.4 Ghz Intel Core i7
32gb RAM 1600 DDR3
OS: 10.8.5