qt creator uses excessive cpu

Qt creator uses as much cpu as it can when I open one of my projects. In my laptop it uses 4 cores at 100% all the time. I even let it run for a few hours to see if it stops, but it didn't. I think that the problem started when I added a library called Eigen.
I'm adding a small example using the Eigen library. Whenever I write anything in main (for example "int a = 0;") it makes the cpu usage also go to 400% for a few seconds. If I remove the Eigen part (i do it with a #ifdef USEEIGEN) Qt creator doesn't have that problem. I guess that the performance problem gets much worse in a larger project like the one I mentioned at the beginning.