Congratulations, SimsLover
I know you'll love your pets.
I did something interesting the past couple of days -- My sim household expanded to a husband and subsequent daughter, and with a total six horses things were getting kind of laggy, so I saved the household, then opened a new copy of Twinbrook and bulldozed EVERYTHING. Thereafter I added new lots, incuding those from Showtime. I even added some extras ... there're a total four restaurants for instance. I also added about 50 homes, including my current ranch and a few other households/homes I've built along the way. I've been playing this newly built town for two days with NO lag whatsoever and I love it much more than the original Twinbrook. The town seems more complete with a broader choice of venue options and I did the layout in a manner more reminiscent of a small midwestern town (city hall in the middle of the town square, surrounded on four sides by the two schools, police and fire stations, and merchant type venues). There are four types of parks situated kind of like one large park behind the schools. It's interesting to note that one of my cat-owning sim households (my singer from Showtime) was designated by the game as the pet adoption source.
One funny thing has occurred: two horses that were sold at the equestrian center decided they wanted to come back home. A few minutes ago (2nd full day after their sale) they turned up in my sims' driveway and would not go away. Two of my human sims voluntarily quit what they were doing and went to brush the two horses. I understand this is likely a glitch in the game, but talk about free will !!! It was touching to say the least.