Please make a pet system that allows players to have pets that follow them around. If scripted properly it will not lag, I have actually made the core for a pet system and it uses very little cpu on both clientside and serverside(following and "tricks" work, need to add polishes to the interface though)
basically with it you have all kinds of different looking pets that follow you and if you say something in chat they do a trick(change gani). Maybe make them able to be put in your house and wander around.
for scripters:
the spawned pets only take about 0.003% cpu time on serverside on a regular playerworld, due to a 0.3 second timeout with clientside interpolation of movement.
As for clientside lag it shouldn't lag, it uses no timeouts.