You might want to take a closer look at your Nvidia Control Panel. In addition to vertical sync, Triple Buffering should be On and also look for the new explicit Max Frame Rate setting -- or is this what you were already using to set to 60 vs. 144? This is new for Nvidia, as of around a year or so ago. Vertical sync itself only works in Full Screen mode, but a Max Frame Rate cap should work in either Full Screen or Windowed.
If you want to try Windowed Mode for greater stability, many players find that
Windowed Borderless Gaming helps it feel more like Full Screen without it really being so.
On Sim creation, RAM usage can get carried away and lead to crashes if we try to make the sim all perfect in one session. What I usually do is establish the sim and their basic looks, then return them to CAS later on using MasterController (although that can be done with testingcheats CAS as well) to finish the job after they are placed in-game. It's the same kind of thing with lot design, it doesn't have to be all perfect in the first go-round and both Edit Town and Build/Buy can also run away with too many resources if we try to do too much all at once.
