Hardware degrades overtime. Check your graphics card temperatures using HWMonitor. If it's spiking really bad, your frame rates are going to fall dramatically or in extreme cases, causing your computer to switch off along with hardware damage.
Likely 2 causes are: -Dust build-up (solution: clean your computer hardware) -Hardware degrade (from aging or from overheating)
StarCraft as a tool only serves to fill the time. Nothing more, nothing less. It's only a game.
I keep several thing about myself hidden from everyone and I do a lot of thinking when playing or watching StarCraft, but those thoughts are my business. StarCraft really doesn't do anything except act as a distraction to re-organize my thoughts.
Here's my profile for analysis. As much as I fanboy it, it don't actually play it that much: Link