@graceymanors Okay, I'd expect there to be a setting somewhere, unless the feature was pullled entirely. (It came with the Creator's Update that caused so much trouble, so that wouldn't be surprising). But I can't boot into Windows right now to look around. And I agree, this isn't worth poking around in the registry.
Edit: (Sorry, I got called away and then didn't refresh the page before posting). If you still want to troubleshoot, I'm happy to keep trying different approaches. 70% is much better, but you might still be able to improve. Just let me know.
So, in the meantime, I'm curious if you ever took steps to get your graphics card formally recognized. Another helpful player pointed out to me that the processor will carry more of a load with a weaker card, and while yours is more than strong enough for all of TS3, the game might not think so. And windowed mode is easier on your hardware than fullscreen, so that would also explain why the CPU usage dropped. The relevant data is the Ratings Info category in the deviceconfig. You can just copy and paste those two lines here, if you want.
Also, for the sake of getting a good benchmark, could you list your CPU use for both fullscreen and windowed mode, playing entirely offline, with a new save in a vanilla folder? The person I want to talk to about this is great with Windows but doesn't know a whole lot about Sims games, so it would be helpful information to have.