Lengthy Material Update Time

I have an assembly consisting of 789 parts. I need to change the material properties for several of the members in the structure to a different steel alloy. I was doing this within simulation by right clicking on the parts in the parts list and selecting the alloy I want to use. It is taking quite some time for the program to update the material for whatever parts I choose. Sometimes on the order of 30 mins. It doesn't seem to reflect the number of parts I choose to update. Simply updating one part takes this amount of time. I don't consider my assembly excessively large, and haven't experienced this behavior before in previous versions of Simulation. This assembly was previously in the 2009 format and updates were much faster. Anyone else experience this?