On the other hand you get mentally insane if you try to work in a way that you do s.th. usefull during the 5-10 min compile times you often have with C++ projects.
When I had to deal with this I would just open the newspaper and read an article in front of my boss.
Slow compile times really mess with your brain. When I wanted to test two different solutions, I would keep multiple separate clones (each one takes about 80GB, mind you) and do the manual equivalent of branch prediction by compiling both, just in case I needed the other one as well.