Pre-load of a lot of game data, methods?

I need to load a large number of texture files and map them onto an sphere to create gameobjects during the startup of my game (making lots of planets). If I create these planet gameobjects in a loop in a script does the frame rate for unity go to zero while the loop is executing? If I want to show an animation of a loading bar or something else how would I do this? Would I have to load my planets in small batches?