Do you have 3x8GB RAM?
Two disk drives may not be enough.
Invest in scratch disk for one thing.
Make sure the system is not used as primary scratch volume for each app.
I said go PC because they do have cheap fast Sandy Bridge and later processors
I've used Windows 8 for a year. I never touch the candy, never different and only better than 7 was in 50 ways. Serious. It is just an OS on top of the hardware and for your apps. Lots and lots of choices and sources for hardware in Brazil that you won't find for Apple products and upgrades, off the shelf. Computers are tools. If Linux can work for you fine. And those that are desperate enough go hackintosh. I don't and can't recommend it.
Make specifically what? more RAM and disk arrays help. PCIe SATA for faster and more storage. SSDs even - not just for system but scratch or Aperture library
You won't see or feel difference in RAM in real world More RAM usually until the system can't cache and CS6 or other apps don't. But less than 16GB you probably do.
Wish there was a mandatory list of hardware, software used, upgrades. Generic "want faster" doesn't tell the story.