Cubase on Mac: confused about ASIO vs. Core Audio

Not sure which subforum this should go in, because it’s about Cubase in general (I use v. 5 but I’m worried that posting in an older subforum won’t get nearly as many views/responses! – and this question applies to all versions of Cubase, anyway)

I run Cubase and Ableton Live both on my quad-core iMac, and have a NI Audio Kontrol 1 audio interface.

In ableton, the Audio Kontrol is selected as the interface, and the driver selected (the only option) is Core Audio.

In Cubase, the Audio Kontrol is also selected, but next to this it says “ASIO driver.” There is no option for Core Audio.

Don’t Macs only use Core Audio? And if so, what is the meaning / relevance of “ASIO” inside Cubase, if running on a Mac?

I’ve read conflicting information about how Cubase handles this situation. Over on Gearlsutz, most threads on this matter devolve into rages about Mac vs. PC for audio performance (don’t want to do that here!) with a majority of people concluding that “Cubase just sucks on a Mac due to the ‘Core Audio’ Bottleneck.”

I was hoping I might get some clearer answers in here to the above Q’s. Is Cubase using CoreAudio drivers and just not listing them (showing ASIO instead)? Is there something I should be changing? (though I see no other options in the device setup and VST connections menus…). Is there an understandable explanation for why I can run literally 3 times (if not more) as many plugins inside an Ableton LIve session, on this exact same system, than I can in Cubase before getting overloads / dropouts / etc?. In Live I average 30+ tracks all with plugin instruments and multiple plugin FX. In Cubase (v. 5, same when demo’ing v.6…not sure about 7 now) I’m lucky if I can get 12 - 15 before having overload trouble. It’s the same system and same audio interface-- which just leaves Cubase to blame, no?

I see numerous Mac-using Cubase users in this forum (not to mention that every online video I see about Cubase seems to be done on a Mac) so I imagine there must be some useful / accurate info about this out there.