Defeature taking foreeeevvvveeerrrr

Has anybody had any luck when using a deafeature on a large assembly?  I am testing this function on a pretty big assembly.  All it does is "calculate";I havent even gotten past step 1.  Working with SW2012 SP4 on core i7 870 machines.  8gb of ram. 

BTW, i did a search for this topic but didn't find any answers, which is why I am starting a new discussion.

SolidworksAssemblies