I have my Sim on unlimited, which does make my game slightly laggy at times, but nothing too bad.
Anyway, what you could do is choose heirs, and limit the kids born in the game. Or just have one child per family, until the population drops a bit. Or you could put aging on, and slowly have the oldest generation die off.
One problem is that you can run into is that there won't be as many houses for the family.
I am the type of player that can have 100 Sims from the get-go, so I have to think about stuff like that. I plan to alternate with the Sims I create. I plan to alternate, one generation the Sims will have multiple kids, while the next only the heir will have kids.