What I mainly disliked about the open world was that you were confined to that world. You couldn't just pop over to Sunset Valley if you lived in Riverview whenever you felt like it. And yes, it was laggy. Even now, playing it on a gaming computer, it still doesn't run smoothly. The loading screens were a nightmare too. I remember that I used to always have a book or something next to the computer whenever I was playing the sims 3 back in the day, because I needed something to if I had to go through a loading screen and be stuck there for like 10 min.
For sims 5, I'd love it if they could open up the neighbourhoods, but keep the worlds closed. If I have to go with one though, I very much prefer sims 4 worlds. The loadingscreens don't bother me, as they're always less than a minute for me.
