The emulator must be pretty advanced - definitely a recompiler rather than an emulator, treating the PowerPC opcodes as some form of object code. Each individual core in the XB1 isn't that much faster than one of the cores in the 360, and as a rule of thumb for CPU emulation you need about 10x the performance for accurate instruction-by-instruction emulation, so this can't be what is happening.
I was thinking that they were recompiling the game binaries and only using the game discs for the game data, but if the titles don't need any changes then that can't be the case.
Biting the hand that feeds IT
