Right. That is true. But, I was thinking about only Atari systems, not other developers. But, you're right. It would be CPU-intensive for sure. I agree. It is hard enough for me to get 3D acceleration, for a certain example, on my Linux and Windows guests on VirtualBox for my iMac, and I have a Intel quad-core i7 and 16 GB of RAM in it. The 3D acceleration slows down the machines down too much if it is checked, but that is experimental on VirtualBox anyway, and I am working with a late 2009 iMac, so it is slower than newer Macs. So, I understand what you mean about emulation and it not being perfect. But, good point anyway. Real hardware trumps emulation all the time. So, yes, I do get that, but thanks for bringing it up anyway.
Anyway, that was just an example. I am no emulation expert, but I am certain it could be harder to emulate older cores for classic video gaming. But, I could be 180º off on that, too. Thanks.