why dosent inventor use multi core threading when creating parts?

Im running an i7 8 core 3.3ghz workstation, when working with relatively simple
parts that are fully constrained, sweeping, extruding,etc.....it takes 60-90 seconds to
get out of not responding. my performance manager says that inventor only uses about 45-50 threads. Is this common to inventor 15 as a program, or something Im missing?