When I preview a mission or load a saved game, I basically see two cycles of loading or whatever it is called. The first fills the green bar very quickly and the second takes ages.
But when when I just loaded a savegame and instantly load it again, the second loading cycle still takes very long. I'm using a SSD, see below for specs.
Youtube video: http://www.youtube.com/watch?v=lluh5-mT9a4
CPU: i7-980X, RAM: 12GB Kingston HyperX, GFX: XFX Radeon HD 5970 Black Edition, MOBO: GA-X58A-UD7 X58, POWER: be quiet P8 1200W ATX 2.3, HDD: 2x Intel X25-M G2 160GB, 2.5", OS: W7Pro 64bit