I feel like Live and Logic do a good job with multi core support.
Live takes each stream of audio and puts it on a core, once your streams (tracks, routings) exceed the core count, they get stacked on to earlier cores.
For an 8 core that means the 9th track will go on the 1st core, 10th the 2nd, and so on.
If you plan to run multiple Reaktor ensembles, more cores is better. And just planning to run Reaktor alone means going for a higher clock speed whenever you can (2.93ghz+)
An 8 core 2010 now, with a 12 core CPU upgrade down the road may cost you less in the end, and is definitely worth researching. I’m not familiar enough with the depreciation rates of the 12 core upgrade services to have a sure idea how well that would pan out, however.[/quote]
Doing a bit of research on this now, since I had heard that Reaktor will only occupy a single core, but apparently this is not the case when used in a host with multicore support which can distribute cores on a per-track basis. That said, there’s also lots of complaints about Live’s multicore support.
Some interesting info contained below:
https://www.native-instruments.com/forum/threads/build-a-computer-that-only-runs-reaktor.261785/ (more Windows than Mac info here, but some interesting testing done)