I think a fully open world (as in TS3) is really hard on memory due to how much needs to be active at the same time. So while the idea is awesome, the execution tends to be really rough on the machines the game is running on.
I think having a semi-open world would work though:
The worlds could still be as they are, with Sims being able to travel between them (via loading screens) and show up as they do now. The same with the travel and movement between neighborhoods within one world. But the neighborhoods themselves, I think, could be open - no loading screens between, say, the three houses in the Pinnacles in Del Sol Valley or the houses around the Goth one. And smaller worlds like Glimmerbrook or Selvadorada could be fully open.
@Simmerville I agree about the info on neighborhood lots. It's even strange that sometimes you have the option to move in a household from the library, despite the fact that a family is already living on that lot.
@AlexSimmerman The simulation lag is unfortunately unconnected to the memory issues that would possibly cause a lag and problems with the open world. It's a bug within the code that seems to come and go and can happen even in small lots and households.
