computer cpu ,memory

running mac osx 10.8.3
i7 2.8 ghz ,12gb

i have up to 12 gb of memory in my computer with a 64 bit operating system
running cubase 7 in 64bit mode has cubase access to all that memory
this also goos for my cpu with my cpu got the impression that with using cubase start spiking
when checking the cpu meter in my operating system seeing that its low and stable