Attacking the CPU is dumb - mobile cpus have not increased significantly in performance, so why pay a premium of more than x% for <x% performance increase to have the latest gen?
Seriously, the GPU is the only thing you're likely to get a big win from at the consumer level, and you're restricted to intel's shitty IGP until you get to the top end MacBook Pro. Again: you are exceedingly unlikely to get a real day-to-day performance increase from the high end intel mobile cpus on a core-for-core basis, and adding a tonne of cores just eats your battery life (hell, ram alone is a significant power drain for laptops, hence the last gens 16gig limit)