CREO 3.0 assembly model regeneration in drawing not responding

I have a relatively complex assembly that's taking forever to generate a drawing view. everytime I change a setting (View Display> no hidden/ no lines/ etc...) but mostly i'll get a 'not responding' so i have to restart CREO. same issue when i try to export a pdf. I can annotate, add dimensions fine though.

some history on the file, it's a heavily modified copy of a previous drawing/assembly file that had the same issue. A coworker managed to solve the unresponsiveness with a setting that affected how CREO is generating the assembly model. Said coworker cannot be reached and i really need help getting this drawing to work. any ideas what it is?