Originally I was thinking of doing the whole game, but that takes like 100 gigs with all the expansion packs and flash drives that big are expensive

External drives with 500 GB to 1 TB storage or so are quite cheap, and last I checked, 128 GB flash drives were cheap too. Sims 3 itself is about 32 GB once you include all expansion and stuff packs, although I can see how your user data might push that number higher.

Having said that, how much free and total space do you have on your computer, and how much of your Sims 3 data is comprised of old saves and custom content you're not currently using? The easiest path would be to move all the extraneous data elsewhere, which would save you the trouble of creating a special setup and also avoid hurting performance. Sims 3 loading times are very sensitive to the speed of the drive that holds the data, and an external drive is almost always going to be slower than an internal one, although exceptions do exist.

To answer the actual question, you might be able to create a symbolic link for just your Mods folder, or perhaps even for just a subfolder. But I've never tested that and can't tell you that it would work as expected, even putting aside the potential performance issues. A much easier fix would be to move data you're not using elsewhere, then swap it out when you need it again. And all of this is dependent on how much space you actually need to clear.

Possible, yes, but there would be a performance drop from having something the game needs constant access to on an external drive. High speed USB can also get quite hot and slow their read/write speed until they cool down, you might not necessarily want to be waiting on a drive to come out of sleep when a lot of CC is in play.

Considering performance is already at a premium for this game, perhaps worth considering turning your focus onto other files or programs? Or a more permanent storage solution, like a small additional HDD or SSD, if budget allows.

It's not *urgent* at the moment, I still have 39 gigs of storage left out of 237 gigs, but the sims is literally pretty much the only high-storage space program I have and I'm planning to download my albums to itunes so I can download them to my phone and download Paralives when it comes out next year so that'll probably make things pretty tight - when you say having it on an external drive is a heavy impact to performance are you mainly talking about loading the stuff in in CAS or with gameplay in general? B/c tbh CAS doesn't worry me so much since loading times are already long and I can just do my stuff in other tabs and check back every so often

Loading here refers to all loading screens: the initial one, travel transitions, entering CAS, going into Edit Town. There would also be more of a delay in loading patterns, so it's not like you can simply take an extended break once per play session to accommodate a single longer loading screen.

To be clear, the amount of an impact using external storage has can vary greatly: it depends on the speed of the drive, sometimes the quality of its controller and whether it has any cache, and the speed of the connection to the computer. I've seen a high-end drive in an enclosure with a much slower connector that prevents the system from maxing out the speed of the drive itself or the port it's connected to on the computer. I've also run an OS from an external drive with no obvious performance hit, because I did my research and bought a drive with third-party benchmarks to prove it could hit its advertised speeds.

The point is that you can't simply say that external drives are always going to be noticeably slower than internal ones. They're almost always technically slower, but the difference can be negligible or massive, or anything in between.

Your music should play back fine if stored on an external drive. I have no idea whether Paralives would benefit from being on an internal drive, but you could find out when it's released. It depends a lot on how the game is programmed, for example Sims 4 isn't impacted as much, in practical terms, as Sims 3. And depending on your model of computer, you might be able to add a secondary internal drive, bypassing this entire discussion. Internal SSDs are very cheap right now, at least compared to traditional prices, and installing one isn't particularly difficult.

Yeah, longer loading screens are fine - I just wanted to confirm that putting the game on an external drive wouldn't slow down the actual process of gameplay when you're in live mode - also, I'll definitely be looking into SSD prices and whether they're compatible with my laptop!