Minimizing Database Hits

I wrote class that contains a function that retrieves users shopping cart items from database and then returns an array with qty, item number , item name, etc. So now whenever I want to retrieve the users cart I use the following: $cart_contents = $cart->get_cart_contents(); I then iterate through $cart_contents to display info. Now I am trying to minimize the number of hits to the database so my question is, am I querying the database every time I call on $cart_contents?