I love how your build is coming along! My favorite is the wellness area. I love how it connects to the orangery. <3 I'm sorry you're having lag, though.
I like having huge spaces for my Sims as well, but I'm very gameplay-minded, so I have no qualms about having empty rooms/spaces if I don't have an idea for them. I'm also guilt-free about it because I think it would be rare to find homes this big with all of the rooms actively used and I hate lag. I have no lag and don't want to do anything to change that. It also helps with the tedium of building everything at once. I built the fundamental rooms first and as my Sims lived there, they added more pictures, decorations and also more rooms. When I needed a 9th bedroom (a nursery), I was able to use the empty/free space to add it rather effortlessly.
All of these big builds make me want to build another small palace for my Sims, but they already have 3 homes (which is a burden) and they can't afford another one right now. I'm also not sure when they'd even have time to use it, but it might be fun to build. I need to focus on properly decorating their second home first, though.
