Found out about this through a thread over in motunation and thought I'd respond here as well. On the system I have (mid 2011 27 inch iMac running OSX 10.9.5 with 32 gig ram) patch change is instantaneous in Digital Performer 8.07 with the au plugin format. Also instantaneous patch change in ProTools 11.3.1 aax plugin format on the same computer.

Jack