Re: The Sims 3 Lagging and Flickering

@canoernek  Do you still get flickering if you don't use compatibility mode for Sims 3?  Please test and let me know.  And if the game runs better for you in compatibility mode, which would be unusual but is certainly possible, I'm curious to know which mode you're using.

Forcing vertical sync, which only applies to fullscreen mode, often helps with flickering.  V-sync is supposed to sync the frames the graphics card produces with the refresh rate of your screen, in this case 60 Hz, so when it's working, you won't see fps above 60.  However, I don't know whether forcing v-sync through the Nvidia Control Panel will work with your particular setup—it often doesn't with dual-card laptops.  Still, it's easy to test, and you don't need to download anything.  Right-click on your desktop and select the Nvidia Control Panel, then Manage 3D settings > Program Settings, and you'll see this:

Choose TS3.exe (without the W) in the green box, then set Vertical sync to On (red box), and click Apply.  You can also try Adaptive and Adaptive (half refresh rate); the latter will cap fps at 30, which may not be what you want but is a good test of whether the setting is applying at all.

If the Control Panel settings don't have any effect, there's a tool called D3D Overrider that allows you to force v-sync in older games.  The tool was last updated in 2014 but still works with Sims 3, if you want to try it.