What Should I Do: SOLVED

I had a big family living in a huge house on that 64x64 lot in Brindleton. I "solved" the problem by paring my household down to just three sims, but that's not a good option for your challenge. I do wonder if it's the size of the lot or if the amount of furnishings in your house that's causing the problem, though. Your castle is beautifully decorated and full of fun stuff to do, but all those options mean more processing time. If your sims are rich enough, consider buying a retail lot and using it as a second home. Only use the residence for screenshots, or activities that can't be done away from home.