The A-57 is around 2.25X more powerful than the A9...
The A15 which has a pipeline identical to A57 is around 2x more powerful than the A9 and 25% less powerful than the A57 -> BUT IS LESS POWER EFFICIENT...
Hey!... i'm sure 64 bit and it could be at least 50% difference in favor A57 compared with A15 for the same code(which is quite remarkable) ... also the ARMv8 is a "clustered" architecture, meaning it will be possible to have more than 4 cores in a single chip... so it may end up being 5x (add more cores) lol...
From 12 ALUs to 72 ALUs... and the CPU side also will have more than double performance( it was if not wrong) 2 ARM A15 cores + 1 ARM A9 big.LITTLE. NOW its 4 A-57 cores + 1 A53 big.LITTLE... smaller process more efficient, and the A57 is more power efficient and the A15, and the A53 is *HALF* the power of A9, so it could be basically the same power envelope.