Also, I was wondering if there are mods that improve performance up to 50-70 fps.

TS3 is a somewhat high.demand game, but it also has some limitations in what resources it is capable of using (32-bit game, can use 2 GB up to around 3.7 GB RAM at the most, and various other issues that arise from a 32-bit game on a 64-bit system - It can run on a 64-bit system, but isn't optimalized for a 64-bit system, so there are flaws), there may be issues with the newest of the new graphic cards, Windows 10 might potentially be an issue, so getting the most powerful laptop ever isn't a guarantee that the game will work, let alone work well. The game itself is also a bit too demanding for the game engine it's built with, Doesn't mean the game won't run, it just means you may have to find ways around the issues. Check out the recommended (not minimum) requirements and use those as a baseline, and maybe read a bit around to see which systems people are still successfully running the game on.

Also, Sims 3: Ultimate collection? Is that a thing now? Or are you confusing it with Sims 2 Ultimate collection? Just wondering. I think you can still get TS3 and all the expansions via Origin or Steam, but I haven't heard of an all-in-one version.

There is no official Sims 3 Ultimate (or Complete) Collection. Those that exist are sold or offered up for download by other parties and are pirated versions.

Also, unless you have a very high refresh rate monitor in mind, fps is not a good indicator of performance for a time management game like TS3. There is no benefit to allowing one's graphics card to generate fps beyond that which one's monitor can interpret. Most laptop screens will be 60 Hz (some a bit higher), so the goal is usually no more than 60 fps. A laptop with a strong enough GPU can achieve that, there will be drops and stutters here and there on most any system, but in fact it becomes necessary to use vertical sync and often frame rate capping to reel things in so as not to promote poor game performance, lag, screen tears, and damage to the card if left unchecked with fps rates fluctuating too high on most modern cards that are strong enough to run all of the expansion packs. Unlike more modern games, TS3 does not have a functional built-in fps limiter.

I have a acer aspire v17 nitro and it runs ts3 pretty well. I use it for sims when not at home. make sure u get a frames limiter tho. with out one it was hitting like 300fps on it.

I have AMD FX-4320, 16 GB RAM and NVidia GTX 750 Ti, which I daresay is a mid-range PC from 2014, a year of the last game update (last relevant game update, not counting 1.69 as relevant) and it still runs the game fine, even in a big world like Moonlight Falls. I do have a frame drops to around 30 FPS, but the game rarely runs bellow that and in that FPS, the game still plays quite smoothly. On top of what was already witen, another important thing is not to flood your game with CC. Only install what you are sure you will use and you should be OK.