Knowing the limits of your engine and working within those limits is expected. The end game crisis is a good example of this - sure its a fun narrative “final boss” but it also fulfills a core function of purging a lot of intensive cpu calcs by killing huge ais and pops. Good example of a nice fusion of performance, fun, and designing around known limits.
If you look at your saves now and go through em you’ll see like 70,000 lines devoted to individual pops. Each pop is still its own object like it was before...with its own happiness, species,faction, job assignment, etc. and the number of active pops in any one gamestste is now exploded and calcs are done on each of them. That’s so much more to keep track of. The “functioning” of populations into some sorta slider mechanic that is based on the planet is what i thought they were doing.
Instead of pops and tiles you have planet X. Planet X has a total population of 5 billion. 50% Human, 25% Energy Robot, 25% Mining Robot. Each grows at different rates per year and effects the % accordingly. Buildings/districts make so many jobs of each type available. The game allocates the “Pops” it the jobs to maximize production based on traits. No individual tiles. The output is determined by an average of all “pops” working at the job. Etc. Players can make certain jobs off limits to certain pops based on rights/template to optimize on his own.
Instead of planets having hundreds of pops checking many jobs planets just have a couple of strings on a per planet basis. It doesn’t matter if the planet/galaxy population is 5 billion, 5 trillion, or 5 quadrillion. It’s just a couple of ints instead of hundreds of objects.
And here we are coming to the very core concept of Stellaris as it is. Devs, don't know on which stage of development, decided to go with this, as far as I know, never really used model for population representation.
The standard way is just an abstract number, or rather a neat seat of numbers. You have colony, and this colony have a number of people (aliens, machines, not important). Then you add stuff - political approval, crime, stability, habitability, growth rate. You might even be fancy and go a little extra, with different species living on the same planet. If you want each species to have some special traits, you could implement this by primitive maths - you take total population and have planetary bonuses be proportional to population. All of this is implemented in Distant Worlds model. It's neat, simple - and it just works, as one corporate mouthpiece semi-recently said.
But Stellaris team wanted something different. Fine by them, they actually tried to have a pretty unique system for their game. Who doesn't want to have something unique for their own game. Problem was, the system required A LOT of work. I played Stellaris (as many others) from day 1. Like Pepperidge farm, I remember. All these shenanigans with ethic shifts, with literally immortal POPs (only way for POP to die was to purge then) and some other things that I might not recall right now. So it took almost 2 years to more or less fix the POP system, and even that had it's problems, mostly with gene-modified species or different types of robots.
Plus tiles, the system directly tied to the game core concept of POPs. It also took a lot of work. As it was already mentioned by a lot of people - the current 2.2 planetary rework is a bit tricksy. They said 'tiles are gone' - that's not true, they are still here. It's just that now we split planet in two parts - buildings and work places these buildings provide. Before that they where tied together - tile and it's building. Right now they are separate - that's all there is to planetary rework, really.
I'm saying all of this to show that it's literally impossible to change POP system for Stellaris into something else, for better or worse. You could tweak a lot of stuff, both to increase performance and to streamline things. For example, I think we could get rid of POP individual ethics - since ethics rework back in don't even know the patch, the global empire attraction modifiers are what's important. Yes, they affect POP individual ethics in the end, but if this is what causing the performance to tank, we could really get rid of this and replace in completely with empire-wide ethics system, instead of having each POPs ethics we would just have a global numbers for ethics and factions. While it's neat to be able to manually purge these pesky liberals, it's not really practical system to have. Or growth slot, or POP binary state (replace it with POP 'fillnes'/health'). These things could be done and some of them would be welcomed.
But there is no way devs would change the whole system. It's build around POPs. Which ties them to tiles. Get rid of that - and you kill the second main feature of this whole game (the main feature would be real-time nature I would say, since there are tons of turn-based space 4x and only a handful of real-times ones).
And, as a last note, there is no need at all in recalculating stuff for every POP in the galaxy all the time. I'm sure that, having a proper time-saving algorithms, you would be able to have a few thousand POPs in the galaxy with little issues.
