use the mac book pro 2009 osx 10.8.5 with cubase 7.06 halion 4, on the street, on the train, I compose, I can guarantee that your internal sound card and not one problem, even at lower latencies.
obvious warms up a bit the mac, it consumes more battery, but I do not see spike ..
8 gb ram,
cubase 32 bit
install the free application memory to control consumption.
install smc fan controll is also free, to control the temperature of the cpu ...
That the world would be without cubase 7 and cmc six pack?
I love this combination, a perfect marriage.