How many houses do you think is the right amount for a world?

There are worlds optimized by modders that make the game really smooth. I believe the modder name of the worlds i've installed is Ella. But someone may be able to confirm. This worlds have a good amount of houses (all optimized so that sims won't get stuck causing lag) and comunity lots have much more visitors i believe because sims walk much better in the world. I don't know how many houses this worlds have but because they are optimized you can add a few more houses than the ones they already have without lag.