i've been teaching myself how to manually defeature imported geometry for about 8 months on-and-off. if rebuilding time is a main concern, i would have used direct editing, surface tools, and a re-export and import to split the spines and threads off as there own bodies. then have them supressed/unsupressed in the desired config. then roll that freeze bar to the bottom for extra. a lot of features will take up time rebuilding, especially if you have "merge result" turned on. (just from my experience) so i re-export and import again to get rid of any features that it has to calculate. only thing left will be imported geometry.
i've been teaching myself how to manually defeature imported geometry for about 8 months on-and-off. if rebuilding time is a main concern, i would have used direct editing, surface tools, and a re-export and import to split the spines and threads off as there own bodies. then have them supressed/unsupressed in the desired config. then roll that freeze bar to the bottom for extra. a lot of features will take up time rebuilding, especially if you have "merge result" turned on. (just from my experience) so i re-export and import again to get rid of any features that it has to calculate. only thing left will be imported geometry.