plus with 6 lights yourrenders will take forever. of course they will. plus with one IBl and one infinite light you get a better sun effect then with lights. with 6 lights it looks like you are in big bulding with 6 lights. you have 6 different shadows. for sun you only need oen shadow. we all know that the light bounces around you(ground,walls) and so the back is lighter.

so faster and more realistic.