@RainaElf: when you count all homeless/service sims it's 105! (and these are just the ones on the Sims Wiki, depending on the EPs you have and lots place, more of those are generated for new roles too and almost immediately) While I usually don't like thread necromancy, there is a lot to discuss here so thank you (really).
The rumored "150 sim" limit: I've seen this as a default limit set by NRaas' StoryProgression mod and it only applies to residential sims there. I have no idea if Twallan took this from EA's coding or not but I've never seen the resident number in an EA town naturally exceed that during playtime or even come close, especially if you're playing vanilla. I remove that cap whenever I play with the mod and while it has gone over 150 (like to 160), it still usually needs my intervention in terms of manually impregnating sims, messing with age spans, recklessly adding to my own household, etc.
That being said, data is stored for EVERY sim that is generated in a save, with the possible exception of carpool/taxi/bus drivers. I actually took a look at my old finished immortal dynasty and it was chugging along with the data of thousands of sims. I did keep my town's residential population higher than it would naturally be through many male sims who had children outside of the household but the real deluge of info is from service sims you may never hire at all.
Hardware influencing EA's story progression: Now I cannot vouch for this on earlier patches, but it hasn't been true for a while, mostly because EA's story progression hasn't done much of anything since the Pets patch or thereabouts. For a while we were testing out if any combo of hardware/EP selections would bring back the coveted townie pregnancies with story progression but it wasn't true in 2013 with 2013 hardware, and isn't true as I sit at a souped-up gaming desktop. What I can vouch for is that there is no shiny graphics card or RAM amount that will stop sims from getting culled. There's also no hard limit to the sims you can save from it...kinda.
This is a tangent but there are three categories of sims that EA will not cull through story progression alone: previously-played sims (whether it was a previously active household or a sim/multiple sims that used to live with you and since moved out), your coworkers, and any sim that comes pre-packaged into a custom world, because they are considered previously played. Custom worlds are an interesting one because a lot of them have more residents than any EA world. Our own Union Cove has over 100 residents and not a single one will die or move out beyond dying of old age eventually or other non-story progression deaths (like meteor strikes).
