Mrok

I got huge performance issue for big part count objects. I've been just building 800+ parts spaceship in 1.4.5 when upgraded to 1.5. It freezes for 6-8 seconds to add single part, and launching this big rocket from VAB takes 2+ minutes of black loading screen. After loading its ok, performance while flying haven't changed much. It's just for building and loading. Anyone can help how to solve it?