I think I have enough room at the moment. I have now over 70 families in houses, using all the packs. I've gone well over the suggested limit of 200 Sims in game now but still having no problems with crashing. It's a gaming computer, getting a bit long in the tooth now with only 8 G memory with a GTX1060 card but plenty of space to use.
I've never used mods, cc or moo though, maybe some of those interfere with the game in ways they don't realise. I remember Maxis cut back on codes a while ago that they let modders use because some might cause problems in the game.
The expanding game has to keep up with the OS's that Microsoft and Macs keep improving on too, so some old machines get left behind. I've had so many machines in my time to keep up with The Sims!