Sunset Valley, Riverview, and Twinbrook are considered the best-made EA worlds in terms of performance, with the fewest issues that would cause stuck sims or anything else that would trip up the game engine. Most EA-made worlds run pretty well though. Aside from Isla Paradiso and Bridgeport, the only other world that gets regular complaints is Starlight Shores, and a lot of the trouble is related to the Showtime career performance limos; NRaas Traffic can take care of that.
I've been playing in Dragon Valley for a while now and have only noticed one problem location: the spot outside the bookstore where sims appear when they get out of their cars. They step into the heather and get stuck, but the heather can be deleted. There are also a few lots that lag for a second or two when entering Build or Buy mode; I'm pretty sure that's because the creators used MoveObjects on to place some of the landscaping, since I only see those issues when the landscaping is layered.
