Any way to make the game run faster?

[Quadrophenia]

So I just got the Sims 3 for my Birthday yesterday and it looks great, the only thing is, it runs slow.
I installed it on my MacBook Air and it plays, but the problem is if I try to make my character do something, he will just stand there not doing anything. So, If he needs to use the bathroom and I tell him to use it, he just stares at it for a minute and then finally goes to urinate.
I'm not really sure why the game runs so slowly but any help would be greatly appreceated.