Ridiculous CPU usage building lighting.

Hey, I have a 2 year old laptop (it was high end at the time), and I'm making an open world game in Unity. My only issue in making the game at the moment is this: Unity uses a huge amount of my CPU when building lighting, which I'd normally be ok with, but the issue is that this causes the CPU to reach ~94 degrees, even with my cooler boost button on (I have an MSI). Usually I stop Unity from building the lighting at this point as to stop my computer from being fried. Is their some way I can make Unity only use say 25% of my CPU instead of everything that isn't already being used? When I turn everything off that I can turn off, no problems happen, but when I go in to play, the Terrain glitches up and flickers black.

Thanks,

Dec_bot

Rig

CPU: i7-4700HQ,

GPU: GeForce GTX 860M (2GB),

Memory: DDRIII(L) 8GB.