The Sims 3 is a massive game, and when you’ve been playing one family for a while, you’ll start to notice a lot of bugs within the game. These can easily be fixed with mods. The Nraas mods do a very good job with fixing most bugs, and there are tons on Mod The Sims to find that fix little issues.
Since adding mods to my game, it runs a lot better. I rarely encounter any bugs. So I obviously recommend modding your game. These mods that fix issues, can also make the game more realistic, but that’s entirely up to you.
Though be wary of the official The Sims 3 store, especially with fan-made content. The stuff that EA make are safe, what fans make are not. I highly recommend that you DO NOT download any CC (custom content) from the TS3 store. There are extremely buggy CC items, from where people have incorrectly made outfits, hairstyles, etc. by assigning them to everything (which is a massive no no). This means that when you have a baby, it will be given that t-shirt you just downloaded, causing your baby to have stretched out limbs and obscuring the world map.
These incorrectly made CC can infect your game, even if the item was not put on the Sim/item you downloaded. The code can still enter your game as it attaches itself to content creator’s creations. It’s like a virus, which messes up your game and it is a pain to get rid of.
If you’re unlucky and you have bad CC in your game, you’ll need to find the code for it and delete it from your files, this will stop you from passing it on to others without realising, but it doesn’t remove it from your game.
To remove it, you’ll need to open up the TS3 launcher, and then scroll through your downloaded content to remove it. There’s also a program you can download, and you can go through every bit of CC you downloaded and delete the CC that has ticked everything. An adult t-shirt should just be ticked for adults, a teen t-shirt should only be ticked for teens etc.
It takes a while to clean, but eventually your game will be clean from them and it’s definitely worth it.
So where is it safe to download CC? Mod the Sims. I’ve downloaded a lot of content from there and it’s all been safe (though check the comments first, just in case it is bad). You should really avoid the TS3 store and just use Mod the Sims. From what I’m aware of, MTS has to moderate everything before it’s posted on their website (I submitted a house I made on TS2 a few years ago, when TS2 was a thing). This means that most of the stuff there is safe, but you should still be careful.
Overall, should you download mods? Yes. A lot of mods are very, very useful. However, make sure you back up your game before installing new mods, in case something goes wrong. Also, make sure you read the guide on the mod you want to download, so you get the right one and know what to do if you want to uninstall it. You’ll also know if there may be any conflictions (which can be pretty harmful to your game, but most of the time, the mod just won’t work).