@silverwood02 There's a big difference between running the base game and maybe one or two early expansion packs versus all packs on high settings. I think you mentioned in another post that you had World Adventures and Ambitions installed on your 2011 computer? (And I guess Late Night, since you asked about celebrities.) Those were the first EPs released, and the demands they place on a system are nothing compared to Pets or Seasons.
I played TS3 on a 2010 macbook pro for six years before I noticed any performance hit, other than the usual issues with running the game in mac OS. But Ambitions was my only pack; I never dared to install any of the demanding ones. I think my Nvidia 330 would probably have melted from the stress, and taken the rest of the laptop with it.
Even many modern processors can't handle the demands of TS3, and that goes for low- and mid-range graphics cards as well. The problem is that the game doesn't really make allowances for weaker hardware, at least not in any useful way. A U-series processor, new as it may be, is still built to run in ultra-low power mode, which translates to something below 2 GHz, depending on the model. TS3's most demanding packs need a sustained processor speed of at least 2.4 GHz to run properly.
There is theoretically a way to force a U-series processor to run at consistent higher speeds, but it's not even clear whether the relevant BIOS data is user accessible, especially on a laptop. And doing so might significantly shorten the CPU's life. U-series models aren't built to withstand the same heavy workload as H- or K-series, or the AMD equivalents.
For the graphics card, any model below an Nvidia 1050 or 950 (or AMD equivalent) just doesn't have the bandwidth to keep up with all the data it's receiving from the most demanding EPs. Again, the early ones are fine, but rendering long-haired pets, or rain and snow, takes graphics processing power that the lower-end cards don't have. And forcing them to try can overheat and damage them; in the worst case scenario, it can damage the rest of the computer as well.
All this doesn't even take into account the cooling necessary to run a game like TS3. Even powerful hardware can damage itself if it's allowed to consistently overheat. And among laptops, it's really only the gaming models that have enough cooling to keep up with the heat produced by a processor and graphics card running TS3.
So this is kind of a long explanation, but it's why we don't recommend people try to run all TS3 packs on a computer that isn't likely to be able to withstand the stress. Even many modern computers aren't built to handle the demands, especially those designed to be light and portable and run things like word processors and browsers. Better to not run TS3 at all, or only play the mildest packs, rather than damage or destroy a laptop by forcing it to perform tasks it was never built to handle.