Maximum population in the save file before sim culling?

I know that the sim culling reason is for game performance. But what makes me feel unsafe to play the game without mods is because I can't control or avoid the game deleting or editing people without my consent.

My play style is to take care of every sim including NPC, If I don't like some, I can delete them manually. I don't like how the game secretly does something like this.

Most of my mods are about to control the damage of unwanted progress that can't opt-out. 😂

If you go into Manage Households, you can click on the Heart to make each household you wish to protect a favorite. Favorited aren't supposed to fall prey to Culling. Hope this helps.

About population increasing

From my experience, there are some places and situations where the game will create a lot of new Sims. For example...

1. Visiting some exotic worlds that have local traits (Ex. Selvadorada, Mt.Komorebi, Tomarang etc.)
2. Visiting the university lots. (If you have Get Famous, the game may pick existing sims instead of making new)
3. Visiting Sixam or Magic Realm. (Other occult worlds didn't spawn as many new sims as those two)

As I don't want to see any new random sims during my playing sessions (for screenshot health), I always let the game add the required sims to the point that they don't need more (and I will fix their appearance before I play that world).

However, some worlds are too needy. In Tomarang, it even needs local vendors. I have to let the game have 2 sets of vendors (2x4) to prevent the new random sims from appearing during the playing session.

I don't mind much about random sims (I can fix it) but it's not convenient (or possible) to enter CAS while playing the story.

I don’t use mods.  Sometimes they would cull townies I had.  But, some time ago they made it where if one of your played sims had a strong relationship with another sim (very high in friendship, enemy, or love ), that it would keep them from being culled.  I’m not sure if it is still that way, but I assume it is. But, if you don’t play and keep up those relationships, they will dwindle over time.   Also, if I really want someone saved I will put them in a house, apartment etc.  so far I haven’t had people I have put in homes or apartments culled.  Also, if you go in and make over a townie, I found they are more likely to stay around.  I have lost mail people, service people, and waitresses.  If you particularly like some of those people you might want to build up and keep a high relationship with them.  I sometimes will cull people myself, but be careful, you may get clumsy waitresses or not so good cooks, etc.