There's a fading animation which lasts for around three seconds when opening and closing/changing the map. The map is likely on average opened hundreds of times in a playthrough as the game doesn't have any HUD. I assume that no loading occurs on the background as the map is a static 2D image.
In the PC version this has been resolved seemingly by speeding up the animation: http://enhanced.townofsilenthill.com/SH2...ransitions
In the PC version this has been resolved seemingly by speeding up the animation: http://enhanced.townofsilenthill.com/SH2...ransitions