UE4 on mac in 2016?

I’ve just installed the editor on my mid 2012 mac pro tower as well. Replaced the graphics card with a GTX 980 (+ 970 and 760 externally). Beefed up the specs a bit because of Octane render. CPU maybe a bit outdated: 2 x 2,4 GHz 6-Core Intel Xeon / 32gb DDR3 RAM
Unreal runs pretty slow, it takes a long time (2-3 minutes) compiling shaders on the most basic of scenes. Starting up also takes about 20-30sec.

Are there any settings that need optimisation on OSX? Or is CPU the bottleneck ?
Unreal Engine beginner here, so maybe someone could point me in the right direction with making it a bit faster.