A seperate program that helps you organize mods better.

It's especially helpful if you primarily mod your game through CurseForge. It cross-references your mods folder with CF to check for mods that have updates.
This only does some of the work if you also download mods from other places, but it's still great.

It can detect duplicate files, and I really appreciate that you can see the CAS previews when in the app.

Organize your Folder!!

I cannot stress this enough. mods WILL break your game at some point. this is more important the bigger your folder gets. Its good to have a lot of seperate folders so isolating the mod causing issues is easier.

for gameplay/script mods, remember that they can't be placed more than one folder deep into your mods folder. because of this I like to separate them by "GAMEPLAY" and "OTHERTS4SCRIPTS"

I also keep mods that are updated often or are particularly important in seperate folders with their version numbers. (MCCC, TMEX Mods, XML injector)

CAS/BB Custom Content should be organized to some extent as well. The way you do this is up to you, as you can have as many folders as you like with .package files.

I like to separate mine by creator name, as it makes things a lot easier than if I were to try to separate them by type. (i tried. not good.)

Ultimately, the way you organize CAS/BB CC doesn't matter too much, and you should do what makes the most sense to you. If it breaks, it's less likely that it'll be game-breaking. And there are tools to delete CC without having to go and find the cooresponding folder/file name.

Bulk Rename Utility is a seperate program that helps you rename large amounts of files.

Removing spaces and special characters from the file names of your mods can help improve loading times. TS4 struggles the most when travelling to different lots, especially if there is a lot of CC present on the lot or your sim.

the program looks complicated, but you just need to select "Sym" and put a Space into the "Char" section under the "Remove" category. (shown in pic below) You can then select which files to rename. (Selecting a folder renames the folder, not files inside of it)

I used this tool on my folder of about 20 GB, and my loading times for travelling went from about 5-10 minutes to 1-3 minutes. This is more impactful on laptops or lower-end PCs

Show Mods at Startup

Turn this OFF!!! This won't improve preformance while in-game, but it will massively improve startup times.

Another seperate program. It's mainly used by CC creators, but has features that are helpful for CC management.

If you click on "My CC" you can view the CC models, swatches, and more info. This also works for Build/Buy CC too. I use this program mostly to edit flags. Having a lot of CC can end up making your menus unorganized, and ruin being able to use filters properly.

I reccomend making a backup before you edit anything, especially if you're not experienced in CC making or editing it in this way.

You can also use this program to merge several .package files into one larger .package file. Some people say that this improves preformance, but it's not a signifigant boost.

Most of the preformance boosts that people report are simply from the lack of special characters in a large amount of files. Or due to the startup menu worsening startup times the more mods you have. (both issues I have explained better ways to fix)

This makes it incredibly hard to remove broken CC, and can also mess up Last/Better Exceptions from identifying the problem. It's reccomended that you don't merge files, and instead organize your CC folder.

If you DO decide to merge packages, back-up your unmerged files somewhere you can return back to when something breaks. You should also try to separate things into a several different merged files to make it easier on yourself. For example, all CC from one creator in one file, or all makeup CC from one creator in one file.

OneDrive Sync

If you're a windows user, you should have OneDrive off. I have my personal opinions about it (it is one of the worst cloud storage options out there, and it's integration with Windows File Explorer is actual dogshit), but it can also fuck with The Sims 4

Having cloud syncing turned on can cause old versions of mods to return, re-breaking things you thought were fixed. This can also happen with Last Exceptions files, which is a particular type of hell to put someone through if they're troubleshooting.

If you are crazy and want to have OneDrive on your computer, im sure theres a way to disable the "Electronic Arts" folder from syncing. Which is good enough ig.