The more bricks a set has, the longer it takes and the worse the performance is. The largest set I had in the game before the release of V2.0 had 1300 bricks. It took around 45 minutes to finish with the cheats I use when testing the game. Without them it would have taken me at least two hours. But if you really want a bigger set, I added one of the two houses from the Pet Shop modular building (975 bricks) in the latest update.