@MisterSidternay Have you taken steps to limit your in-game framerates? If not, and you'd like help with this, let me know. If you have done this, please confirm that the imposed limit is working by bringing up the cheats console (ctrl-shift-C) and entering fps on . The fps counter will appear in the upper-right corner.
If this doesn't or didn't help, please test with no mods other than those from NRaas, and if you use NRaas StoryProgression, turn it down to the lowest setting. You don't need to save your progress.
If this doesn't help either, let me know what world(s) you're playing in. Please also let me know how much RAM Sims 3 is using immediately after you load a save and the game clock starts running, and how much it uses after about 20 real-time minutes. You can put the game into windowed mode (but don't minimize it) and have a look at the Task Manager.