The beauty of Dirac Live not only limits itself to great results but it's also linked to the proprietary structure allowing a mix of IIR & FIR to reach the lowest latency. In the case of the DDRC series, the overall latency is 23mS. A minor latency compared to other room correction products, but still to be accounted for if you plan to have a hybrid setup (i..e some speakers Dirac Live processed and others not). You'd want to provide time alignment in that case.
Some of you are now thinking, why so much latency? I want a 0s latency! :-) In a perfect world, we'd agree but I think that it will be very hard to find a room correction algorithm (doing something meaningful) with very low latency for some simple reasons. Digital Room Correction like Dirac aims at solving room acoustic aberration (i.e. airwaves traveling through the room and bouncing on walls). The longer the processing latency, the higher the frequency resolution we can achieve in the low frequency. If you want to solve acoustic issues, you need longer processing inside the DSP to process the sound correctly. That's pretty much the reason.
The IIR filters are very quick to perform simple equalization resulting in low latency. But as you may have noticed, none of them will be able to make your room sound the way Dirac does. Tradeoffs Tradeoffs. :-)