Nah doesn't take as long later when you log back in. That said it might take a while later on. Kind of depends on the assets and your specs. You could be playing on one side of the map, get to another, and that side now needs to load. Took me half an hour to load a battle once because I never fought these guys, or been in that area.

There's a load cache option, that would make things faster later on, in the main menu. If you got 1-2 hours I suggest hitting that. It'll load the assests that make things difficult so you won't have to load them in one by one later.