Flickering slow rendering

GreenOak1357​  The GPU memory rating only goes up to 4, so that's fine.  But I would get rid of the OVERRIDE part.  The section of GraphicsRules.sgr should looke like this:

if ($textureMemory == 0)
  seti textureMemory 2048
  # setb textureMemorySizeOK false

The important part is the # in the third line (after the two spaces that are already there on that line).  That tells the game that this is not an override but your actual VRAM.  I know you have more, but even 1024 would be sufficient for the highest rating, and Sims 3 can only use 800 MB video memory anyway.

Aside from that, please turn down high-detail lots to 2, and if that alone doesn't help, turn water to Mirrors Only.  Do the latter at the Main Menu, then quit to desktop before loading the save.

Please test in both fullscreen and windowed modes.