Bungie has already stated that the long load times are due to the fact that they have been putting patches out at a far larger rate than planned and has caused this issue. Bungie has also already said that a patch is in the works that Bungie hope will reduce this problem by cutting the time by half. Keep a eye on the "This Week at Bungie" and any patch notes for more info as to when Bungie are ready to implement the fix.