I am not sure what you problem is but copy and pasting vectorial fills in 3d will result in convertion to lines. Not a very desirable arrangment as it will increase file size and complexitiy of the redraw. Editing could become a nightmare. Maybe your converted stucco pattern is taxing your video card too much.
BTW I put all my section views in separate windows. One thing I really hate is getting a drawing from someone who has put all their sections or elevations into one window. Future editing and changes ar a pain and become untrustworthy particulary inregard to real levels or dimensions.
Also as you hve noted the window can get overloaded with too much "line" information.
When I first started with Archicad (over 12 years ago) I had noone to help me. I still vividly remember creating an office reflected ceiling plan where I used lines to create everything including the light fittings ( which of course should of be objects). The screen redraw times were ridiculously long.
Cheers John
John Hyland : ARINA : www.arina.biz
User ver 4 to 12 - Jumped to v22 - so many options and settings!!!
OSX 10.15.6 [Catalina] : Archicad 22 : 15" MacBook Pro 2019 [/size]