Recommended requirements for Sims 4 and all packs?

@waterywatermelon  A laptop or desktop Nvidia GTX 1650 can run all Sims 4 packs together on ultra settings, with some room to spare.  A 1050 ti can as well, although the laptop version is cutting it a bit close; the faster cards in previous generations can also be fine.  Any 5000- or 6000-series AMD card is more than fast enough, with the possible exception of the 5300M, as are the 570, 580, and similar older cards.

I could go into the other recommended specs, but it's easier to talk about specific hardware rather than describe all the details related to each component.  If you want to know about your current system or a new one you're considering buying, please list the specs or link a product page.

The issue is that Sims 4 itself lags for reasons that are unrelated to the speed of the graphics card.  Of course the processor might not be able to keep up, but even without hardware issues, the game can have slowdowns for various reasons, or no apparent reason at all.  If you look at a hardware monitoring report, you can see that a CPU and GPU might not be close to maxed out, yet fps is dropping or sims are standing around doing nothing.  This is the game engine's fault, perhaps (but definitely not always) exacerbated by mods.

There's no reason you can't play with most of your packs at once.  All game and stuff packs should be fine—a couple of game packs add a little bit to the demands of Sims 4, and SPs barely have any impact at all—as should the early expansions.  Cats & Dogs is the first demanding one, but I don't think the newer ones are all equally problematic.  For some, it's situational, for example Eco Lifestyle can cause lag when the NAP votes come in, and you might find that performance drops when the eco footprint is green.  But you can disable certain features without removing the entire pack.

As for how to uninstall a pack, it's certainly possible, but the only supported way is to uninstall the entire game and reinstall without that pack.  Or you could manually delete the pack folders.  Either way though, Origin will still try to reinstall any missing packs, sometimes even if you have auto game updates disabled.  So the easier method is to disable those packs in Origin:

https://sims4.crinrict.com/eng/2017/03/disable-single-packs/

Snowy Escape is one of a few new packs that appears separately in the Control Panel, for reasons I personally haven't heard.  Origin would probably try to reinstall it at some point as well.

@puzzlezaddictThanks for the long, detailed and thorough response.

I just have a Nvidia GeForce GT 730 graphics card, and with it, I play The Sims 2 Ultimate Collection. I also play The Sims 3 with 8 expansion packs (everything except ShowTime, Island Paradise and Into The Future) and 2 stuff packs. The Sims 2 UC on Origin and The Sims 4 on Origin are the only ones that come as one whole thing, while The Sims 3 packs can all be uninstalled separately. Even my old Sims 2 discs (that I don't have installed anymore because of the UC) could be uninstalled separately. How come The Sims 4 is designed in a way so that you can't uninstall individual packs?

This is my hardware:
Intel(R) Core(TM) i5-6400 CPU @ 2.70GHz 2.71 GHz
8.00 GB RAM
64-bit operating system, x64-based processor
Nvidia GeForce GT 730

I also play The Sims 2 Ultimate Collection on Origin, and that one comes with all expansions and stuffs, and so far, it has the best performance out of all three. Because of having the best performance, it is the only game that I play with high settings for a lot of the options but some things are unimportant to me like smooth edges/anti-aliasing. I just keep that as low as possible, and it is also a performance booster. The only times when The Sims 2 lags for me are Sim-generating times (that is, whenever a Sim is being generated randomly by the game) or whenever the game is preparing the NPCs for aging up into the next lifestage (FreeTime expansion feature). With that said, are there examples of reasons for The Sims 4 lag/low FPS rate? Or, is it just what you said above (NPC voting in Eco Lifestyle, possible game engine lag). 

@waterywatermelon  Your processor is more than sufficient for ultra settings in all three games, as is 8 GB RAM, although it would be best to keep the multitasking to a minimum while playing Sims 4.  You could also add more memory if you wanted: it's about the easiest upgrade there is.  I don't know what kind of hard drive(s) are in your computer, but given its age, you might have no solid state drive at all, or else one that's too small to hold your games.  In that case, adding one and installing Sims 3 on it would make for a significant improvement; Sims 4 would be less affected, and Sims 2 probably not at all.

You could also upgrade the graphics card, but your options would depend on the power supply and whether it has (or you're comfortable adding) one or two power cables that would run from the PSU to the card.  If you're not sure, just list the specs of the PSU: manufacturer, wattage, and rating.  The space inside the case also matters, specifically the length between the back of the case and the first obstruction, measured along the length of the graphics card or its slot.

If you're thinking of getting a new system, of course none of the above matters.

Sims 2 is the least demanding of these games by far, so it's no surprise you're able to play without much trouble.  Sims 3 is actually less forgiving on lower-end systems than Sims 4, although the requirements for ultra settings are essentially the same at this point.  As for why slowdowns happen in Sims 4, yes, there are plenty of other reasons, probably including some sim generation as in Sims 2, but I haven't really looked into it.  In Sims 3, the game seems to create new NPC sims as a save is loading, so you wouldn't necessarily see any lag, just a loading time that's a minute or two longer than expected.  Lag usually comes from the game engine trying to reroute stuck sims, or from similarly endless loops, but in many scenarios, if the issue didn't resolve, you'd llikely see a crash before long rather than extended lag.

As for why Sims 4 doesn't have a convenient way to uninstall individual packs, I believe it has more to do with Origin than anything else.  Most Origin games' DLC has a trivial impact compared to the base game, and therfore there wouldn't be much cause to uninstall that DLC.  So the feature was never built into Origin.  It's not currently in the EA Desktop App either, although that's still in beta.  Disc installs predate Origin, and the installers were often built for their specific game, so there was more room to add features that only that game might need.

@puzzlezaddictSo, I just checked for the type of hard drive, and it's a hard disk drive. The computer was purchased in 2016. It has only been about 5 years.

I usually don't do multi-tasking or have multiple windows while playing The Sims 4. It's usually The Sims 4 that is open. But, if I open the Task Manager, I can find a long list of background processes and apps.

Lag usually comes from the game engine trying to reroute stuck sims, or from similarly endless loops,

I think part of the reason why the Sims 2 runs more smoothly is that the game does not reroute stuck Sims. If Sims can't get to the destination, they will just stop what they are doing, and they may do something else instead. Also, it's a closed world, not open world, so all pathways are located on the lot. As long as the lot is all routable, it's fine.

@waterywatermelon  I didn't mean that your computer was extremely old, just that at the time it was assembled (the processor is six years old, which gives me a ballpark), it wasn't common to include a large SSD, especially for a lower-end or mid-range system.  SSDs were quite expensive even a few years ago.  Now though, you could get one of these:

https://www.amazon.com/dp/B07G3KGYZQ

https://www.amazon.com/dp/B07YD579WM

or the higher-end option:

https://www.amazon.com/dp/B089C73T72

stick it in a drive bay, plug in two cables, and have much faster loading times.  I don't know whether your motherboard has an M.2 slot—some of its generation do, some don't—but if it does, you could instead install an NVMe SSD in that slot, without plugging in anything else, and get even faster read and write speeds.

https://www.amazon.com/dp/B086BGWNY8

https://www.newegg.com/western-digital-blue-sn550-nvme-500gb/p/N82E16820250134

https://www.bhphotovideo.com/c/product/1437035-REG/intel_ssdpeknw010t8x1_660p_1tb_ssd_pci.html

https://www.amazon.com/dp/B07YFFX5MD

I'm not saying you need to, exactly, but having an SSD is a significant quality of life upgrade, particularly if you take the time to reinstall Windows on the SSD, which is simple to do.

And again, you could upgrade the GPU if you wanted, and perhaps relatively cheaply if you're willing to buy a used product on Ebay or have a friend who's upgrading to a brand-new card and would sell you their old one.

None of this addresses the fact that Sims 4 will run slowly sometimes.  It just means that the slowdowns are not as dramatic or as frequent, and of course that you could use higher settings.