Hi im having the same problem in Unity 5. My 3000p+ welded ship perform well(about 20FPS after launched) in Unity 4 version KSP, but in 1.1.2 and 1.1.3 it even cant be launched from the SPH(always blackscreen)! when i only launch the welded deck of the ship(1000p+), the FPS was only about 5 ,same as the unwelded one ,seems the weld now only strengthen the craft ,but cant increase FPS......