I am using OSX 10.10.2 with photoshop CC 2014 and intuos 4.
I had been experiencing similar problems described here and I found that the only way to make photoshop cc 2014 work as intended without lag is to go full screen mode without menus. i.e only canvas and press tab to hide all menus. Hopefully this will help adobe to narrow down what is the bug that continues to disrupt our workflow. This is just a temporary solution and really hope adobe can patch this to make it work out.
With that said, I still do experience my wacom suddenly stop working and have to unplug it and plug in again for it to continue working as per normal in photoshop cc 2014. But this could be another problem that maybe wacom should address.