Cantabile will automatically leverage the extra processing power of multi-core and multi-processor computers. Parallel racks are processed simultaneously and many other background processes are also done in parallel.
Since some plugins don't behave correctly when used in this manner, Cantabile also includes a compatibility mode that still leverages multi-core processors but in a less aggressive manner.
Of course if you're still using a single core machine, Cantabile's highly optimized audio engine ensures you'll still get the absolute best performance possible. Many users of Cantabile 1.2 have reported that Cantabile consistantly outperforms many other hosts.