I recommend using "Linking" method for bringing screws to the scene. This method makes viewport work better and allows for faster rendering. 

For linking screws in Blender: 

File ••••• Link •••• Open file  (screw_heads_kit.blend) ••••• Collection ••••• pick your screw type from S1-20

If you want to change the material faster for linked screws, use addon “Edit Linked Library”.

Before adding screws to the scene, look for the file  SCREW_HEADS_KIT_NUMBER_MAP.jpg  for the exact screw number.